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Only strip invariant.load from special pointers #57386

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Only strip invariant.load from special pointers #57386

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7b6646f
Only strip invariant.load from special pointers
vchuravy Feb 13, 2025
a679390
Update test/llvmpasses/late-lower-gc.ll
vchuravy Feb 13, 2025
25aeb46
fixup! Update test/llvmpasses/late-lower-gc.ll
vchuravy Feb 14, 2025
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6 changes: 4 additions & 2 deletions src/llvm-late-gc-lowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1979,8 +1979,10 @@ bool LateLowerGCFrame::CleanupIR(Function &F, State *S, bool *CFGModified) {
// strip all constant alias information, as it might depend on the gc having
// preserved a gc root, which stops being true after this pass (#32215)
// similar to RewriteStatepointsForGC::stripNonValidData, but less aggressive
if (I->getMetadata(LLVMContext::MD_invariant_load))
I->setMetadata(LLVMContext::MD_invariant_load, NULL);
if (auto *LI = dyn_cast<LoadInst>(I)){
if (isSpecialPtr(LI->getPointerOperand()->getType()) && LI->getMetadata(LLVMContext::MD_invariant_load))
LI->setMetadata(LLVMContext::MD_invariant_load, NULL);
}
if (MDNode *TBAA = I->getMetadata(LLVMContext::MD_tbaa)) {
if (TBAA->getNumOperands() == 4 && isTBAA(TBAA, {"jtbaa_const", "jtbaa_memoryptr", "jtbaa_memorylen", "tbaa_memoryown"})) {
MDNode *MutableTBAA = createMutableTBAAAccessTag(TBAA);
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14 changes: 14 additions & 0 deletions test/llvmpasses/late-lower-gc.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,20 @@ top:
ret void
}

; Confirm that `invariant.load` on other loads survive
define void @gc_keep_invariant(float addrspace(1)* %0) {
top:
; CHECK-LABEL: @gc_keep_invariant
%pgcstack = call {}*** @julia.get_pgcstack()
%1 = bitcast {}*** %pgcstack to {}**
%current_task = getelementptr inbounds {}*, {}** %1, i64 -12

; CHECK: %current_task = getelementptr inbounds ptr, ptr %1, i64 -12
%2 = load float, ptr addrspace(1) %0, align 4, !invariant.load !1
; CHECK-NEXT: %2 = load float, ptr addrspace(1) %0, align 4, !invariant.load
ret void
}

define i32 @callee_root({} addrspace(10)* %v0, {} addrspace(10)* %v1) {
top:
; CHECK-LABEL: @callee_root
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