Fix metal segfault by check vectorValue before accessing (#7688)

gtong-nv · csyonghe · github-actions[bot] · web-flow · commit e3afef145e67 · 2025-07-11T20:16:10.000Z
* Check vectorValue before accessing

* Fix metal segfault by using IRElementExtract for general vector handling

Address review comments by replacing IRMakeVector-specific code with
IRElementExtract to handle any vector instruction type (IRIntCast, etc).
This makes the code more robust and fixes cases where float2(1,2)
creates IRIntCast instead of IRMakeVector.

Co-authored-by: Yong He &lt;csyonghe@users.noreply.github.com&gt;

* Fix sign comparison warning in metal legalize

Cast originalElementCount-&gt;getValue() to UInt to avoid comparison between signed and unsigned integers.

Co-authored-by: Yong He &lt;csyonghe@users.noreply.github.com&gt;

---------

Co-authored-by: Yong He &lt;yonghe@outlook.com&gt;
Co-authored-by: github-actions[bot] &lt;41898282+github-actions[bot]@users.noreply.github.com&gt;
Co-authored-by: Yong He &lt;csyonghe@users.noreply.github.com&gt;
diff --git a/source/slang/slang-ir-metal-legalize.cpp b/source/slang/slang-ir-metal-legalize.cpp
@@ -32,10 +32,18 @@ void legalizeImageStoreValue(IRBuilder& builder, IRImageStore* imageStore)
             }
         }
         elementType = valueVectorType->getElementType();
-        auto vectorValue = as<IRMakeVector>(originalValue);
-        for (UInt i = 0; i < vectorValue->getOperandCount(); i++)
+
+        // Extract components using IRElementExtract to handle any vector instruction type
+        if (auto originalElementCount = as<IRIntLit>(valueVectorType->getElementCount()))
         {
-            components.add(vectorValue->getOperand(i));
+            for (UInt i = 0; i < (UInt)originalElementCount->getValue(); i++)
+            {
+                auto elementExtract = builder.emitElementExtract(
+                    elementType,
+                    originalValue,
+                    builder.getIntValue(builder.getIntType(), i));
+                components.add(elementExtract);
+            }
         }
     }
     else
diff --git a/tests/metal/texture-store-vector.slang b/tests/metal/texture-store-vector.slang
@@ -0,0 +1,16 @@
+//TEST:SIMPLE(filecheck=CHECK): -target metal
+
+// Test that we can compile texture store operations with 2-component vectors
+// without segfaulting. This reproduces the issue where legalizeImageStoreValue
+// would crash when trying to expand a float2 to float4 for Metal texture writes.
+
+RWTexture2D<float2> output;
+
+[shader("compute")]
+[numthreads(32, 32, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    // This should expand float2(1,2) to float4(1,2,0,0)
+    // CHECK: {{.*}}float4(1.0, 2.0,
+    output.Store(dispatchThreadID.xy, float2(1, 2));
+} 

Original file line number	Diff line number	Diff line change
`@@ -32,10 +32,18 @@ void legalizeImageStoreValue(IRBuilder& builder, IRImageStore* imageStore)`
`32`	`32`	`}`
`33`	`33`	`}`
`34`	`34`	`elementType = valueVectorType->getElementType();`
`35`		`- auto vectorValue = as<IRMakeVector>(originalValue);`
`36`		`- for (UInt i = 0; i < vectorValue->getOperandCount(); i++)`
	`35`	`+`
	`36`	`+ // Extract components using IRElementExtract to handle any vector instruction type`
	`37`	`+ if (auto originalElementCount = as<IRIntLit>(valueVectorType->getElementCount()))`
`37`	`38`	`{`
`38`		`- components.add(vectorValue->getOperand(i));`
	`39`	`+ for (UInt i = 0; i < (UInt)originalElementCount->getValue(); i++)`
	`40`	`+ {`
	`41`	`+ auto elementExtract = builder.emitElementExtract(`
	`42`	`+ elementType,`
	`43`	`+ originalValue,`
	`44`	`+ builder.getIntValue(builder.getIntType(), i));`
	`45`	`+ components.add(elementExtract);`
	`46`	`+ }`
`39`	`47`	`}`
`40`	`48`	`}`
`41`	`49`	`else`