2013/7/24 Rico Schüller kgbricola@web.de:
dlls/d3dx9_36/tests/shader.c | 308 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 308 insertions(+)
This is okay, but as a followup can you add some tests with mixed-type structs? Something like:
struct { float f; int i; bool b; };
If you have already written tests of this kind, I'd like to know what does the compiler do in this case :)
Hi Matteo,
please see the attached patch.
On 25.07.2013 16:13, Matteo Bruni wrote:
2013/7/24 Rico Schüller kgbricola@web.de:
dlls/d3dx9_36/tests/shader.c | 308 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 308 insertions(+)
This is okay, but as a followup can you add some tests with mixed-type structs? Something like:
struct { float f; int i; bool b; };
If you have already written tests of this kind, I'd like to know what does the compiler do in this case :)
Single variables could only have the tested types (I was not able to generate other conversions than bool->bool, int->int, int->float, bool->float, float->float). But I found a way to do it with structs and there I found some issues. Hence this has to be fixed in wine, too. Thanks for the nice question. :-)
Basically you got these for the struct: 1. D3DXRS_FLOAT4: if one variable is used as float or a float variable is used or an int variable is used as bool (the compiler may do some optimization), else #2 2. D3DXRS_BOOL: if a bool variable is used as bool (in an if clause), else #3 3. D3DXRS_INT4
It looks like you could only do it that way with unused variables. I'm not sure if this makes sense at all. Why would someone set an unused variable? Maybe I missed something? Do you know anything else?
Cheers Rico
2013/7/30 Rico Schüller kgbricola@web.de:
Hi Matteo,
please see the attached patch.
On 25.07.2013 16:13, Matteo Bruni wrote:
2013/7/24 Rico Schüller kgbricola@web.de:
dlls/d3dx9_36/tests/shader.c | 308 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 308 insertions(+)
This is okay, but as a followup can you add some tests with mixed-type structs? Something like:
struct { float f; int i; bool b; };
If you have already written tests of this kind, I'd like to know what does the compiler do in this case :)
Single variables could only have the tested types (I was not able to generate other conversions than bool->bool, int->int, int->float, bool->float, float->float). But I found a way to do it with structs and there I found some issues. Hence this has to be fixed in wine, too. Thanks for the nice question. :-)
Basically you got these for the struct:
- D3DXRS_FLOAT4: if one variable is used as float or a float variable is
used or an int variable is used as bool (the compiler may do some optimization), else #2 2. D3DXRS_BOOL: if a bool variable is used as bool (in an if clause), else #3 3. D3DXRS_INT4
It looks like you could only do it that way with unused variables. I'm not sure if this makes sense at all. Why would someone set an unused variable? Maybe I missed something? Do you know anything else?
It does make some sense, although this is not what I expected. Also, I'm getting different results...
If I understand correctly your test, all the fields of a structure share the same registerset. Which is silly, since AFAIU each member of the structure has a separate D3DXCONSTANT_DESC in the constant table, both on disk and in memory, there is no point the compiler should force the same registerset for all the struct members.
Under the constraint of forcing all the members in the same registerset, the "conversion rules" you mention make sense. In SM3 an if bool can be replaced by an if_comp with a float register and a rep/loop, which is controlled by an integer constant, can be emulated via loop unrolling (although I'm not sure how the compiler can possibly do that for the shader in your testcase). These are also pretty much the only use cases of bool and int constants and there are no int or bool "non-constant" registers so essentially no other type conversion is possible. You can check the plain text output from fxc to see how those constants are used in the shader code and how did the compiler manage to convert those constants from one type to another.
I tried to compile your HLSL shader myself (I had to disable optimization though, otherwise compilation fails) and, assuming the text output of fxc matches what actually ends up in the shader bytecode, in general I'm getting different struct members in different registersets. E.g. snbf gets allocated to c6-c9 and b8. FWIW, I used fxc from the June 2010 DirectX SDK, on Windows 7. I'm not sure why my results are different from yours. Or am I misunderstanding the test?
BTW, what needs to be fixed in Wine? I couldn't see anything obvious by reading the test.
Cheers, Matteo.
Cheers Rico
On 31.07.2013 00:14, Matteo Bruni wrote:
2013/7/30 Rico Schüller kgbricola@web.de:
Hi Matteo,
please see the attached patch.
On 25.07.2013 16:13, Matteo Bruni wrote:
2013/7/24 Rico Schüller kgbricola@web.de:
dlls/d3dx9_36/tests/shader.c | 308 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 308 insertions(+)
This is okay, but as a followup can you add some tests with mixed-type structs? Something like:
struct { float f; int i; bool b; };
If you have already written tests of this kind, I'd like to know what does the compiler do in this case :)
Single variables could only have the tested types (I was not able to generate other conversions than bool->bool, int->int, int->float, bool->float, float->float). But I found a way to do it with structs and there I found some issues. Hence this has to be fixed in wine, too. Thanks for the nice question. :-)
Basically you got these for the struct:
- D3DXRS_FLOAT4: if one variable is used as float or a float variable is
used or an int variable is used as bool (the compiler may do some optimization), else #2 2. D3DXRS_BOOL: if a bool variable is used as bool (in an if clause), else #3 3. D3DXRS_INT4
It looks like you could only do it that way with unused variables. I'm not sure if this makes sense at all. Why would someone set an unused variable? Maybe I missed something? Do you know anything else?
It does make some sense, although this is not what I expected. Also, I'm getting different results...
If I understand correctly your test, all the fields of a structure share the same registerset. Which is silly, since AFAIU each member of the structure has a separate D3DXCONSTANT_DESC in the constant table, both on disk and in memory, there is no point the compiler should force the same registerset for all the struct members.
Yes, they share all the same registerset. The optimization seems to force only the type of the register (it optimizes the not used members out).
Under the constraint of forcing all the members in the same registerset, the "conversion rules" you mention make sense. In SM3 an if bool can be replaced by an if_comp with a float register and a rep/loop, which is controlled by an integer constant, can be emulated via loop unrolling (although I'm not sure how the compiler can possibly do that for the shader in your testcase). These are also pretty much the only use cases of bool and int constants and there are no int or bool "non-constant" registers so essentially no other type conversion is possible. You can check the plain text output from fxc to see how those constants are used in the shader code and how did the compiler manage to convert those constants from one type to another.
I tried to compile your HLSL shader myself (I had to disable optimization though, otherwise compilation fails) and, assuming the text output of fxc matches what actually ends up in the shader bytecode, in general I'm getting different struct members in different registersets. E.g. snbf gets allocated to c6-c9 and b8. FWIW, I used fxc from the June 2010 DirectX SDK, on Windows 7. I'm not sure why my results are different from yours. Or am I misunderstanding the test?
The bytecode should match the result in the text output. Also after some additional test these structs seem to set several registers (as could be seen in the text), so the constant table constant desc is not able to give a full description for these. So an app should not depend on those or did I miss something? It's getting tricky again. E.g.: struct {float f2; int n2; bool b2;} snb; sets: D3DXRS_FLOAT4 15,16 (60-68) D3DXRS_BOOL 3,4,5 (3-6)
I'll send an update to the tests to cover these issue. I think I have to look at the binary and whats really in there. Hopefully that information could be found somewhere ...
I'm also using the June 2010 SDK tools, but on wine. The problem might be, that "fixme:d3d9:Direct3DShaderValidatorCreate9 stub" will not fail here. If I disable optimization, I get (I think the same you got): // Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 2 // sbnf b8 1 // sn c0 3 // sbn c3 3 // sbnf c6 3 // sbnf2 c9 3 // sbnf3 c12 3 // snb c15 2
This is what I get (header.fx is the text file containing the shader) for the shader in the test without disabling anything: wine fxc.exe /E main /Tvs_3_0 header.fx // Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 3 // sbnf b9 2 // sn i0 3 // sbnf3 i3 3 // sbnf2 i6 2 // sbnf c0 3 // sbnf2 c3 3 // sbnf3 c6 3
I'm using this receipt to generate the binary blob: wine fxc.exe /E main /Tvs_3_0 /Fo temporary.fxo header.fx 1>2 od -v -t x4 -A n -w32 temporary.fxo | sed 's/ /, 0x/g' | sed 's/^, //g' | sed 's/$/,/g'
It doesn't make a difference if you pass a valid or invalid shader to the constant table interface. I think both should work fine. The question is, why does the compiler produce code which may fail on your system? I guess this will fail on any machine... are there systems where this code works? Or is it the nature of the compiler to produce only sometimes code which works when using optimization?
BTW, what needs to be fixed in Wine? I couldn't see anything obvious by reading the test.
I got 104 test failures with this test case. Those are only in the part when converting float <-> int <-> bool... Yeah, you couldn't see those from just reading the code. ;-)
I've attached a new test with a shader binary without optimization. The results are the same, only the register usage changed (and the shader size).
Cheers Rico
2013/8/1 Rico Schüller kgbricola@web.de:
On 31.07.2013 00:14, Matteo Bruni wrote:
2013/7/30 Rico Schüller kgbricola@web.de:
Hi Matteo,
please see the attached patch.
On 25.07.2013 16:13, Matteo Bruni wrote:
2013/7/24 Rico Schüller kgbricola@web.de:
dlls/d3dx9_36/tests/shader.c | 308 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 308 insertions(+)
This is okay, but as a followup can you add some tests with mixed-type structs? Something like:
struct { float f; int i; bool b; };
If you have already written tests of this kind, I'd like to know what does the compiler do in this case :)
Single variables could only have the tested types (I was not able to generate other conversions than bool->bool, int->int, int->float, bool->float, float->float). But I found a way to do it with structs and there I found some issues. Hence this has to be fixed in wine, too. Thanks for the nice question. :-)
Basically you got these for the struct:
- D3DXRS_FLOAT4: if one variable is used as float or a float variable is
used or an int variable is used as bool (the compiler may do some optimization), else #2 2. D3DXRS_BOOL: if a bool variable is used as bool (in an if clause), else #3 3. D3DXRS_INT4
It looks like you could only do it that way with unused variables. I'm not sure if this makes sense at all. Why would someone set an unused variable? Maybe I missed something? Do you know anything else?
It does make some sense, although this is not what I expected. Also, I'm getting different results...
If I understand correctly your test, all the fields of a structure share the same registerset. Which is silly, since AFAIU each member of the structure has a separate D3DXCONSTANT_DESC in the constant table, both on disk and in memory, there is no point the compiler should force the same registerset for all the struct members.
Yes, they share all the same registerset. The optimization seems to force only the type of the register (it optimizes the not used members out).
Under the constraint of forcing all the members in the same registerset, the "conversion rules" you mention make sense. In SM3 an if bool can be replaced by an if_comp with a float register and a rep/loop, which is controlled by an integer constant, can be emulated via loop unrolling (although I'm not sure how the compiler can possibly do that for the shader in your testcase). These are also pretty much the only use cases of bool and int constants and there are no int or bool "non-constant" registers so essentially no other type conversion is possible. You can check the plain text output from fxc to see how those constants are used in the shader code and how did the compiler manage to convert those constants from one type to another.
I tried to compile your HLSL shader myself (I had to disable optimization though, otherwise compilation fails) and, assuming the text output of fxc matches what actually ends up in the shader bytecode, in general I'm getting different struct members in different registersets. E.g. snbf gets allocated to c6-c9 and b8. FWIW, I used fxc from the June 2010 DirectX SDK, on Windows 7. I'm not sure why my results are different from yours. Or am I misunderstanding the test?
The bytecode should match the result in the text output. Also after some additional test these structs seem to set several registers (as could be seen in the text), so the constant table constant desc is not able to give a full description for these. So an app should not depend on those or did I miss something? It's getting tricky again. E.g.: struct {float f2; int n2; bool b2;} snb; sets: D3DXRS_FLOAT4 15,16 (60-68) D3DXRS_BOOL 3,4,5 (3-6)
I'll send an update to the tests to cover these issue. I think I have to look at the binary and whats really in there. Hopefully that information could be found somewhere ...
The constant table could easily represent the situation by specifying different register sets for different struct members. But apparently the generated constant table is just broken. I ran the test with WINEDEBUG=d3dx and this is an excerpt of the trace I got:
trace:d3dx:parse_ctab_constant_type name sbnf, elements 1, index 6, defaultvalue 0x18e1d0, regset D3DXRS_FLOAT4 trace:d3dx:parse_ctab_constant_type class D3DXPC_STRUCT, type D3DXPT_VOID, rows 1, columns 3, elements 1, struct_members 3 trace:d3dx:parse_ctab_constant_type name b4, elements 1, index 6, defaultvalue 0x18e1d0, regset D3DXRS_FLOAT4 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_BOOL, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name n4, elements 1, index 7, defaultvalue 0x18e1e0, regset D3DXRS_FLOAT4 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_INT, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name f4, elements 1, index 8, defaultvalue 0x18e1f0, regset D3DXRS_FLOAT4 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_FLOAT, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name sbnf, elements 1, index 8, defaultvalue 0x18e124, regset D3DXRS_BOOL trace:d3dx:parse_ctab_constant_type class D3DXPC_STRUCT, type D3DXPT_VOID, rows 1, columns 3, elements 1, struct_members 3 trace:d3dx:parse_ctab_constant_type name b4, elements 1, index 8, defaultvalue 0x18e124, regset D3DXRS_BOOL trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_BOOL, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name n4, elements 1, index 9, defaultvalue 0x18e128, regset D3DXRS_BOOL trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_INT, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name f4, elements 1, index 9, defaultvalue 0x18e12c, regset D3DXRS_BOOL trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_FLOAT, rows 1, columns 1, elements 1, struct_members 0
Instead of generating an entry for the struct with the correct members, the compiler generates TWO entries for sbnf, one with all its fields in D3DXRS_FLOAT4 and the other with D3DXRS_BOOL. Which, if I'm reading this correctly, makes 0 sense. Calling GetConstantByName() on the various fields then happen to return the first instance of the struct. It's the same with native d3dx9, FWIW.
So this looks even more broken than we thought for struct constants. You're right when you say that the application can't depend on this. I assume that this means the application has to explicitly force each field to a known location via the "register" keyword in the shader, or (and this would be AWESOME) just blindly set the shader constants which happened to be used by those fields in previous compilation of the shader. Great...
I'm also using the June 2010 SDK tools, but on wine. The problem might be, that "fixme:d3d9:Direct3DShaderValidatorCreate9 stub" will not fail here. If I disable optimization, I get (I think the same you got): // Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 2 // sbnf b8 1 // sn c0 3 // sbn c3 3 // sbnf c6 3 // sbnf2 c9 3 // sbnf3 c12 3 // snb c15 2
This is what I get (header.fx is the text file containing the shader) for the shader in the test without disabling anything: wine fxc.exe /E main /Tvs_3_0 header.fx // Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 3 // sbnf b9 2 // sn i0 3 // sbnf3 i3 3 // sbnf2 i6 2 // sbnf c0 3 // sbnf2 c3 3 // sbnf3 c6 3
I'm using this receipt to generate the binary blob: wine fxc.exe /E main /Tvs_3_0 /Fo temporary.fxo header.fx 1>2 od -v -t x4 -A n -w32 temporary.fxo | sed 's/ /, 0x/g' | sed 's/^, //g' | sed 's/$/,/g'
Yeah, that matches my results.
It doesn't make a difference if you pass a valid or invalid shader to the constant table interface. I think both should work fine. The question is, why does the compiler produce code which may fail on your system? I guess this will fail on any machine... are there systems where this code works? Or is it the nature of the compiler to produce only sometimes code which works when using optimization?
Well, probably the optimizations are just broken. On the other hand the compiler would produce an error in these cases (but only on Windows and also not a particularly helpful error message... oh well). BTW, the shader generated by disabling the validation would fail at CreateVertexShader() time on Windows (when it would be validated again).
BTW, what needs to be fixed in Wine? I couldn't see anything obvious by reading the test.
I got 104 test failures with this test case. Those are only in the part when converting float <-> int <-> bool... Yeah, you couldn't see those from just reading the code. ;-)
I've attached a new test with a shader binary without optimization. The results are the same, only the register usage changed (and the shader size).
Cheers Rico
I see. Not sure how much that actually matters, since setting the bool field via the constant table wouldn't do the right thing anyway. I guess it depends on the specific tests failing.
Matteo.
On 01.08.2013 17:25, Matteo Bruni wrote:
Instead of generating an entry for the struct with the correct members, the compiler generates TWO entries for sbnf, one with all its fields in D3DXRS_FLOAT4 and the other with D3DXRS_BOOL. Which, if I'm reading this correctly, makes 0 sense. Calling GetConstantByName() on the various fields then happen to return the first instance of the struct. It's the same with native d3dx9, FWIW.
Yes, that's exactly the issue. The structs are in there two times with the same name. Maybe you could query the members somehow in a way we wouldn't expect it. At least you could query the struct constant by index instead of by name. After that you may get the correct member and set that single member. This may or may not set the other registers. That also needs a separate test case. What's broken is then only setting the whole struct. For now I think we should gather some information and add a fixme. As it is not possible to have two variables with the same name in the hlsl shader, what do you think about the attached patch? This way we would see apps use this tricky feature.
So this looks even more broken than we thought for struct constants. You're right when you say that the application can't depend on this. I assume that this means the application has to explicitly force each field to a known location via the "register" keyword in the shader, or (and this would be AWESOME) just blindly set the shader constants which happened to be used by those fields in previous compilation of the shader. Great...
Well the "register" theory needs also a test.
I'm also using the June 2010 SDK tools, but on wine. The problem might be, that "fixme:d3d9:Direct3DShaderValidatorCreate9 stub" will not fail here. If I disable optimization, I get (I think the same you got): // Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 2 // sbnf b8 1 // sn c0 3 // sbn c3 3 // sbnf c6 3 // sbnf2 c9 3 // sbnf3 c12 3 // snb c15 2
This is what I get (header.fx is the text file containing the shader) for the shader in the test without disabling anything: wine fxc.exe /E main /Tvs_3_0 header.fx // Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 3 // sbnf b9 2 // sn i0 3 // sbnf3 i3 3 // sbnf2 i6 2 // sbnf c0 3 // sbnf2 c3 3 // sbnf3 c6 3
I'm using this receipt to generate the binary blob: wine fxc.exe /E main /Tvs_3_0 /Fo temporary.fxo header.fx 1>2 od -v -t x4 -A n -w32 temporary.fxo | sed 's/ /, 0x/g' | sed 's/^, //g' | sed 's/$/,/g'
Yeah, that matches my results.
It doesn't make a difference if you pass a valid or invalid shader to the constant table interface. I think both should work fine. The question is, why does the compiler produce code which may fail on your system? I guess this will fail on any machine... are there systems where this code works? Or is it the nature of the compiler to produce only sometimes code which works when using optimization?
Well, probably the optimizations are just broken. On the other hand the compiler would produce an error in these cases (but only on Windows and also not a particularly helpful error message... oh well). BTW, the shader generated by disabling the validation would fail at CreateVertexShader() time on Windows (when it would be validated again).
Ok, I think the optimization problem is another issue. It only produces a "bad" shader.
BTW, what needs to be fixed in Wine? I couldn't see anything obvious by reading the test.
I got 104 test failures with this test case. Those are only in the part when converting float <-> int <-> bool... Yeah, you couldn't see those from just reading the code. ;-)
I've attached a new test with a shader binary without optimization. The results are the same, only the register usage changed (and the shader size).
Cheers Rico
I see. Not sure how much that actually matters, since setting the bool field via the constant table wouldn't do the right thing anyway. I guess it depends on the specific tests failing.
Matteo.
Lets see, I'll try to improve the test. At least we know now that it does some funky stuff. The failures are probably related to the structs are more then one time present.
Cheers Rico
2013/8/1 Matteo Bruni matteo.mystral@gmail.com:
Instead of generating an entry for the struct with the correct members, the compiler generates TWO entries for sbnf, one with all its fields in D3DXRS_FLOAT4 and the other with D3DXRS_BOOL. Which, if I'm reading this correctly, makes 0 sense. Calling GetConstantByName() on the various fields then happen to return the first instance of the struct. It's the same with native d3dx9, FWIW.
I take this partially back, actually it might make sense after all. Calling GetConstantDesc in general returns an array of D3DXCONSTANT_DESC, not necessarily just one. I always wondered why but I failed to make the connection to this case, until now.
Long wall of text follows, sorry. Case in point:
// Registers: // // Name Reg Size // ------------ ----- ---- // sb b0 3 // snb b3 3 // sbn b6 2 // sbnf b8 1 // sn c0 3 // sbn c3 3 // sbnf c6 3 // sbnf2 c9 3 // sbnf3 c12 3 // snb c15 2
Notice how there is an overallocation of the constants: for sbnf there are 3 float AND one bool registers allocated. Now, checking again +d3dx output but tracing some more stuff:
trace:d3dx:parse_ctab_constant_type name sbnf, elements 1, defaultvalue 0x18e1d0 trace:d3dx:parse_ctab_constant_type regset D3DXRS_FLOAT4, regidx 6, regcount 3 trace:d3dx:parse_ctab_constant_type class D3DXPC_STRUCT, type D3DXPT_VOID, rows 1, columns 3, elements 1, struct_members 3 trace:d3dx:parse_ctab_constant_type name b4, elements 1, defaultvalue 0x18e1d0 trace:d3dx:parse_ctab_constant_type regset D3DXRS_FLOAT4, regidx 6, regcount 0 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_BOOL, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name n4, elements 1, defaultvalue 0x18e1e0 trace:d3dx:parse_ctab_constant_type regset D3DXRS_FLOAT4, regidx 7, regcount 0 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_INT, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name f4, elements 1, defaultvalue 0x18e1f0 trace:d3dx:parse_ctab_constant_type regset D3DXRS_FLOAT4, regidx 8, regcount 0 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_FLOAT, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name sbnf, elements 1, defaultvalue 0x18e124 trace:d3dx:parse_ctab_constant_type regset D3DXRS_BOOL, regidx 8, regcount 1 trace:d3dx:parse_ctab_constant_type class D3DXPC_STRUCT, type D3DXPT_VOID, rows 1, columns 3, elements 1, struct_members 3 trace:d3dx:parse_ctab_constant_type name b4, elements 1, defaultvalue 0x18e124 trace:d3dx:parse_ctab_constant_type regset D3DXRS_BOOL, regidx 8, regcount 0 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_BOOL, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name n4, elements 1, defaultvalue 0x18e128 trace:d3dx:parse_ctab_constant_type regset D3DXRS_BOOL, regidx 9, regcount 0 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_INT, rows 1, columns 1, elements 1, struct_members 0 trace:d3dx:parse_ctab_constant_type name f4, elements 1, defaultvalue 0x18e12c trace:d3dx:parse_ctab_constant_type regset D3DXRS_BOOL, regidx 9, regcount 0 trace:d3dx:parse_ctab_constant_type class D3DXPC_SCALAR, type D3DXPT_FLOAT, rows 1, columns 1, elements 1, struct_members 0
Sure enough, if you call GetConstantDesc() for sbnf, passing an array of two D3DXCONSTANT_DESC and setting the count to 2, you get both filled. Same with its struct members. Here's what I get from a quickly hacked test with native d3dx9:
shader.c:6243: sbnf (0) registerset is 2. shader.c:6244: sbnf (0) registerindex is 6. shader.c:6245: sbnf (0) registercount is 3. shader.c:6243: sbnf (1) registerset is 0. shader.c:6244: sbnf (1) registerindex is 8. shader.c:6245: sbnf (1) registercount is 1.
shader.c:6243: sbnf.b4 (0) registerset is 2. shader.c:6244: sbnf.b4 (0) registerindex is 6. shader.c:6245: sbnf.b4 (0) registercount is 1. shader.c:6243: sbnf.b4 (1) registerset is 0. shader.c:6244: sbnf.b4 (1) registerindex is 8. shader.c:6245: sbnf.b4 (1) registercount is 1.
shader.c:6243: sbnf.n4 (0) registerset is 2. shader.c:6244: sbnf.n4 (0) registerindex is 7. shader.c:6245: sbnf.n4 (0) registercount is 1. shader.c:6243: sbnf.n4 (1) registerset is 0. shader.c:6244: sbnf.n4 (1) registerindex is 9. shader.c:6245: sbnf.n4 (1) registercount is 0.
shader.c:6243: sbnf.f4 (0) registerset is 2. shader.c:6244: sbnf.f4 (0) registerindex is 8. shader.c:6245: sbnf.f4 (0) registercount is 1. shader.c:6243: sbnf.f4 (1) registerset is 0. shader.c:6244: sbnf.f4 (1) registerindex is 9. shader.c:6245: sbnf.f4 (1) registercount is 0.
The 0 or 1 in parentheses indicate that the line refers to the first or the second D3DXCONSTANT_DESC respectively. Apparently the registers assigned to a struct are allocated to its members in order, until they run out. This also matches with the output from fxc, if you look at the generated code in particular. On MSDN, in the page for GetConstantDesc, it mentions something about RegisterCount being 0 in some cases (then failing to say anything meaningful on the when and the why). I guess this is pretty much it.
I haven't tested it, but I also expect that setting the value of one of those struct members via the constant table (e.g. SetFloat(device, "sbnf.f4", f)) updates all the "instances" of the constant.
As for the why it is done like this, I guess that's because the compiler might potentially need to have the same constant in multiple registersets (because of the lack of orthogonality between the D3D opcodes and the data types). But it's just a guess.
It looks like quite a number of changes to our ID3DXConstantTable are necessary for this. As far as I can see, the current code for computing the register count for struct members is okay already. What's missing is the ability to store and return multiple D3DXCONSTANT_DESC for each constant and to update all the locations on calls to the various Set* functions as well (assuming that's what actually happens). There might be more but I can't think of anything else right now. Probably it's best to start with fixing / adding tests...
Cheers, Matteo.
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Matteo Bruni -
Rico Schüller