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

* 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 <csyonghe@users.noreply.github.com>

* Fix sign comparison warning in metal legalize

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

Co-authored-by: Yong He <csyonghe@users.noreply.github.com>

---------

Co-authored-by: Yong He <yonghe@outlook.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Yong He <csyonghe@users.noreply.github.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/metal/texture-store-vector.slang b/tests/metal/texture-store-vector.slang
new file mode 100644
index 000000000..0f63b7ce3
--- /dev/null
+++ 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));
+} 
\ No newline at end of file