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Fix assert due to unreachable discard #7289

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Merged
amaiorano merged 2 commits into from
Apr 2, 2025
Merged

Fix assert due to unreachable discard #7289

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3e839b6
Fix assert due to unreachable discard
amaiorano Apr 1, 2025
6ff0fca
Fix test
amaiorano Apr 1, 2025
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4 changes: 4 additions & 0 deletions tools/clang/lib/CodeGen/CGStmt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -525,6 +525,10 @@ void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {

// HLSL Change Begins.
void CodeGenFunction::EmitDiscardStmt(const DiscardStmt &S) {
// Skip unreachable discard.
if (!HaveInsertPoint())
return;

CGM.getHLSLRuntime().EmitHLSLDiscard(*this);
}
// HLSL Change Ends.
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21 changes: 21 additions & 0 deletions tools/clang/test/DXC/FinishCodeGen/unreachable-discard.hlsl
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
// RUN: %dxc /T ps_6_5 -fcgl %s | FileCheck %s

// Compiling this HLSL would trigger an assertion:
// While deleting: void (i32, float)* %dx.hl.op..void (i32, float)
// Use still stuck around after Def is destroyed: call void @"dx.hl.op..void (i32, float)"(i32 120, float -1.000000e+00), !dbg <0x503000001cc8>
// Error: assert(use_empty() && "Uses remain when a value is destroyed!")
// File: <snip>/src/external/DirectXShaderCompiler/lib/IR/Value.cpp(83)
//
// Bug was fixed in CodeGenFunction::EmitDiscardStmt by skipping the emission of
// an unreachable discard.

// CHECK: define void @main()
// CHECK: br label %
// CHECK-NOT: call void @"dx.hl.op..void (i32, float)"
// CHECK: ret void

void main() {
while (true) {
}
discard;
}