[PATCH v2 0/1] MR10555: gdiplus/tests: Fix flaky rounding error in test_getblend.

[Bartosz Kosiorek (＠gang65)]

The sentinel value 0xdeadbeef (3735928559) exceeds the 24-bit mantissa
precision of a 32-bit float. On some architectures (like i386 using
x87 FPU), comparisons between register-stored constants and memory-stored
floats would fail due to inconsistent rounding.

Replaced the sentinel with 12345.0, which can be represented exactly
in a 32-bit float, ensuring deterministic test results across different
floating-point units.

--
  v2: gdiplus/tests: Fix flaky rounding error in test_getblend.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10555

[PATCH v2 1/1] gdiplus/tests: Fix flaky rounding error in test_getblend.

[Bartosz Kosiorek]

From: Bartosz Kosiorek <[e-mail]>

The sentinel value 0xdeadbeef (3735928559) exceeds the 24-bit mantissa
precision of a 32-bit float. On some architectures (like i386 using
x87 FPU), comparisons between register-stored constants and memory-stored
floats would fail due to inconsistent rounding.

Replaced the sentinel with 12345.0, which can be represented exactly
in a 32-bit float, ensuring deterministic test results across different
floating-point units.
---
 dlls/gdiplus/tests/brush.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/dlls/gdiplus/tests/brush.c b/dlls/gdiplus/tests/brush.c
index ad2712fae34..50ebda6aaa8 100644
--- a/dlls/gdiplus/tests/brush.c
+++ b/dlls/gdiplus/tests/brush.c
@@ -202,12 +202,14 @@ static void test_getblend(void)
     status = GdipGetPathGradientBlend(NULL, NULL,  NULL,  1);
     expect(InvalidParameter, status);
 
-    blends[0] = (REAL)0xdeadbeef;
-    pos[0]    = (REAL)0xdeadbeef;
+    /* 12345.0f fits perfectly within the 24-bit mantissa of an IEEE 754 32-bit float,
+       avoiding x87 vs SSE rounding discrepancies */
+    blends[0] = 12345.0f;
+    pos[0]    = 12345.0f;
     status = GdipGetPathGradientBlend(brush, blends, pos, 1);
     expect(Ok, status);
     expectf(1.0, blends[0]);
-    expectf((REAL)0xdeadbeef, pos[0]);
+    expectf(12345.0f, pos[0]);
 
     GdipDeleteBrush((GpBrush*) brush);
 }
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10555

[PATCH v2 0/1] MR10555: gdiplus/tests: Fix flaky rounding error in test_getblend. - approved

[Esme Povirk (＠madewokherd)]

This merge request was approved by Esme Povirk.
-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10555