Fix WGSL sign function to return correct int type instead of float (#7739)

* Initial plan

* Fix WGSL sign function to return int type properly

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Add vector version check for WGSL sign function test

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

* Fix FileCheck order in WGSL sign test - use DAG for order-independent checking

Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: csyonghe <2652293+csyonghe@users.noreply.github.com>

2 files changed, 33 insertions, 2 deletions

diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index 1dcb0b7d4..1443843a9 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -13107,7 +13107,7 @@ int sign(T x)
             };
         else
             return __int_cast<int>(spirv_asm {OpExtInst $$T result glsl450 SSign $x});
-    case wgsl: __intrinsic_asm "sign";
+    case wgsl: __intrinsic_asm "i32(sign($0))";
     }
 }
 
@@ -13131,7 +13131,7 @@ vector<int, N> sign(vector<T, N> x)
             };
         else
             return __int_cast<int>(spirv_asm {OpExtInst $$vector<T,N> result glsl450 SSign $x});
-    case wgsl: __intrinsic_asm "sign";
+    case wgsl: __intrinsic_asm "vec$N0<i32>(sign($0))";
     default:
         VECTOR_MAP_UNARY(int, N, sign, x);
     }
diff --git a/tests/cross-compile/sign-wgsl.slang b/tests/cross-compile/sign-wgsl.slang
new file mode 100644
index 000000000..60e0fceee
--- /dev/null
+++ b/tests/cross-compile/sign-wgsl.slang
@@ -0,0 +1,31 @@
+// sign-wgsl.slang
+
+//TEST:SIMPLE(filecheck=WGSL): -target wgsl -entry main -stage compute
+
+// Test that sign function returns correct type for WGSL
+// WGSL's sign returns float but Slang's sign should return int
+
+struct OutputBuffer
+{
+    int scalar_result;
+    int2 vector_result;
+};
+
+[[vk::binding(0, 0)]]
+RWStructuredBuffer<OutputBuffer> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void main()
+{
+    // Test scalar sign function
+    int scalar_result = sign(0.5);
+    
+    // Test vector sign function  
+    int2 vector_result = sign(float2(1.5, -0.5));
+    
+    outputBuffer[0].scalar_result = scalar_result;
+    outputBuffer[0].vector_result = vector_result;
+    
+    // WGSL-DAG: i32(sign(
+    // WGSL-DAG: vec2<i32>(sign((vec2<f32>
+}
\ No newline at end of file