[llvm] 3a6be12 - [instsimplify] Simplify HaveNonOverlappingStorage per review suggestion on D120133 [NFC]
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Fri Feb 18 11:33:34 PST 2022
Author: Philip Reames
Date: 2022-02-18T11:33:15-08:00
New Revision: 3a6be124cc01191ec52192017791bb04a6c7295a
URL: https://github.com/llvm/llvm-project/commit/3a6be124cc01191ec52192017791bb04a6c7295a
DIFF: https://github.com/llvm/llvm-project/commit/3a6be124cc01191ec52192017791bb04a6c7295a.diff
LOG: [instsimplify] Simplify HaveNonOverlappingStorage per review suggestion on D120133 [NFC]
Added:
Modified:
llvm/lib/Analysis/InstructionSimplify.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index b3459b5ffb01..7475b995cbd8 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2555,20 +2555,24 @@ static bool HaveNonOverlappingStorage(const Value *V1, const Value *V2) {
//
// So, we'll assume that two non-empty allocas have
diff erent addresses
// for now.
- auto isByValArg = [](const Value *V) {
- const Argument *A = dyn_cast<Argument>(V);
- return A && A->hasByValAttr();
+
+ auto isByValArgOrGlobalVarOrAlloca = [](const Value *V) {
+ if (const Argument *A = dyn_cast<Argument>(V))
+ return A->hasByValAttr();
+ return isa<AllocaInst>(V) || isa<GlobalVariable>(V);
};
- // Byval args are backed by store which does not overlap with each other,
- // allocas, or globals.
- if (isByValArg(V1))
- return isa<AllocaInst>(V2) || isa<GlobalVariable>(V2) || isByValArg(V2);
- if (isByValArg(V2))
- return isa<AllocaInst>(V1) || isa<GlobalVariable>(V1) || isByValArg(V1);
+ if (!isByValArgOrGlobalVarOrAlloca(V1) ||
+ !isByValArgOrGlobalVarOrAlloca(V2))
+ return false;
- return isa<AllocaInst>(V1) &&
- (isa<AllocaInst>(V2) || isa<GlobalVariable>(V2));
+ // Both sides being globals shouldn't reach here - as the resulting compare
+ // is a constantexpr - but we want to guard against it to be safe. The
+ // semantics of globals are complicated by e.g. unnamed_addr. The assumption
+ // in this code is that while two globals could end up overlapping, they'll
+ // never overlap with any alloca or byval, and thus we can still reason about
+ // *one* global and one *non* global as disjoint storage.
+ return !isa<GlobalVariable>(V1) || !isa<GlobalVariable>(V2);
}
// A significant optimization not implemented here is assuming that alloca
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