[PATCH] D114647: [TrivialDeadness] Introduce API separating two different usages
Anna Thomas via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 1 11:05:16 PST 2021
anna updated this revision to Diff 391084.
anna added a comment.
addressed review comments
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D114647/new/
https://reviews.llvm.org/D114647
Files:
llvm/include/llvm/Transforms/Utils/Local.h
llvm/lib/Transforms/Utils/Local.cpp
Index: llvm/lib/Transforms/Utils/Local.cpp
===================================================================
--- llvm/lib/Transforms/Utils/Local.cpp
+++ llvm/lib/Transforms/Utils/Local.cpp
@@ -402,6 +402,18 @@
return wouldInstructionBeTriviallyDead(I, TLI);
}
+bool llvm::wouldInstructionBeTriviallyDeadOnUnusedPaths(
+ Instruction *I, const TargetLibraryInfo *TLI) {
+ // Instructions that are "markers" and have implied meaning on code around
+ // them (without explicit uses), are not dead on unused paths.
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
+ if (II->getIntrinsicID() == Intrinsic::stacksave ||
+ II->getIntrinsicID() == Intrinsic::launder_invariant_group ||
+ II->isLifetimeStartOrEnd())
+ return false;
+ return wouldInstructionBeTriviallyDead(I, TLI);
+}
+
bool llvm::wouldInstructionBeTriviallyDead(Instruction *I,
const TargetLibraryInfo *TLI) {
if (I->isTerminator())
Index: llvm/include/llvm/Transforms/Utils/Local.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/Local.h
+++ llvm/include/llvm/Transforms/Utils/Local.h
@@ -90,6 +90,14 @@
bool wouldInstructionBeTriviallyDead(Instruction *I,
const TargetLibraryInfo *TLI = nullptr);
+/// Return true if the result produced by the instruction has no side effects on
+/// any paths other than where it is used. This is less conservative than
+/// wouldInstructionBeTriviallyDead which is based on the assumption
+/// that the use count will be 0. An example usage of this API is for
+/// identifying instructions that can be sunk down to use(s).
+bool wouldInstructionBeTriviallyDeadOnUnusedPaths(
+ Instruction *I, const TargetLibraryInfo *TLI = nullptr);
+
/// If the specified value is a trivially dead instruction, delete it.
/// If that makes any of its operands trivially dead, delete them too,
/// recursively. Return true if any instructions were deleted.
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