[MemCpyOpt] Merge alias metadatas when replacing arguments#67539
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@llvm/pr-subscribers-llvm-transforms ChangesFix mis-compilation encountered in https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Failing.20tests.20when.20rustc.20is.20compiled.20with.201.20CGU. I marked it as a draft PR because I haven't got an appropriate test case yet. Full diff: https://github.com/llvm/llvm-project/pull/67539.diff 1 Files Affected:
diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 4db9d1b6d309afd..e818f6d4e84627d 100644
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -336,6 +336,17 @@ static bool writtenBetween(MemorySSA *MSSA, BatchAAResults &AA,
return !MSSA->dominates(Clobber, Start);
}
+// Update AA metadata
+static void combineAAMetadata(Instruction *ReplInst, Instruction *I) {
+ // FIXME: MD_tbaa_struct and MD_mem_parallel_loop_access should also be
+ // handled here, but combineMetadata doesn't support them yet
+ unsigned KnownIDs[] = {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
+ LLVMContext::MD_noalias,
+ LLVMContext::MD_invariant_group,
+ LLVMContext::MD_access_group};
+ combineMetadata(ReplInst, I, KnownIDs, true);
+}
+
/// When scanning forward over instructions, we look for some other patterns to
/// fold away. In particular, this looks for stores to neighboring locations of
/// memory. If it sees enough consecutive ones, it attempts to merge them
@@ -1096,16 +1107,9 @@ bool MemCpyOptPass::performCallSlotOptzn(Instruction *cpyLoad,
MSSA->getMemoryAccess(C));
}
- // Update AA metadata
- // FIXME: MD_tbaa_struct and MD_mem_parallel_loop_access should also be
- // handled here, but combineMetadata doesn't support them yet
- unsigned KnownIDs[] = {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
- LLVMContext::MD_noalias,
- LLVMContext::MD_invariant_group,
- LLVMContext::MD_access_group};
- combineMetadata(C, cpyLoad, KnownIDs, true);
+ combineAAMetadata(C, cpyLoad);
if (cpyLoad != cpyStore)
- combineMetadata(C, cpyStore, KnownIDs, true);
+ combineAAMetadata(C, cpyStore);
++NumCallSlot;
return true;
@@ -1961,6 +1965,7 @@ bool MemCpyOptPass::processImmutArgument(CallBase &CB, unsigned ArgNo) {
<< " " << CB << "\n");
// Otherwise we're good! Update the immut argument.
+ combineAAMetadata(&CB, MDep);
CB.setArgOperand(ArgNo, MDep->getSource());
++NumMemCpyInstr;
return true;
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Here's a simple example for the memcpyopt+dse combination: https://llvm.godbolt.org/z/EnbPsqab1 |
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I've rebased this over a test case. LGTM
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Thanks a lot! |
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(cherry picked from commit d5c8b23)
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Alias metadata may no longer be valid after replacing the call argument. Fix this by merging it with the memcpy alias metadata. This fixes a miscompilation encountered in https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Failing.20tests.20when.20rustc.20is.20compiled.20with.201.20CGU. (cherry picked from commit 4e6e476)
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Alias metadata may no longer be valid after replacing the call argument. Fix this by merging it with the memcpy alias metadata. This fixes a miscompilation encountered in https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Failing.20tests.20when.20rustc.20is.20compiled.20with.201.20CGU. (cherry picked from commit 4e6e476)
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Alias metadata may no longer be valid after replacing the call argument. Fix this by merging it with the memcpy alias metadata. This fixes a miscompilation encountered in https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Failing.20tests.20when.20rustc.20is.20compiled.20with.201.20CGU.
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Local branch amd-gfx 5512cfe Merged main:34ee53c9e390 into amd-gfx:85bfd92dd479 Remote branch main 4e6e476 [MemCpyOpt] Merge alias metadatas when replacing arguments (llvm#67539)
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Fix mis-compilation encountered in https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Failing.20tests.20when.20rustc.20is.20compiled.20with.201.20CGU.
I marked it as a draft PR because I haven't got an appropriate test case yet.We may want to merge pr without additional test cases first.