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[EarlyCSE] Don't DSE across readnone functions that may throw

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Summary: Depends on D28740

Reviewers: dberlin, chandlerc, hfinkel, majnemer

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D28741

llvm-svn: 292249
This commit is contained in:
Sanjoy Das 2017-01-17 20:15:47 +00:00
parent ea4bdd6b81
commit 659705e7a7
2 changed files with 22 additions and 6 deletions
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13
lib/Transforms/Scalar/EarlyCSE.cpp
View File

@ -761,12 +761,13 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
continue;
}
// If this instruction may read from memory, forget LastStore.
// Load/store intrinsics will indicate both a read and a write to
// memory. The target may override this (e.g. so that a store intrinsic
// does not read from memory, and thus will be treated the same as a
// regular store for commoning purposes).
if (Inst->mayReadFromMemory() &&
// If this instruction may read from memory or throw (and potentially read
// from memory in the exception handler), forget LastStore. Load/store
// intrinsics will indicate both a read and a write to memory. The target
// may override this (e.g. so that a store intrinsic does not read from
// memory, and thus will be treated the same as a regular store for
// commoning purposes).
if ((Inst->mayReadFromMemory() || Inst->mayThrow()) &&
!(MemInst.isValid() && !MemInst.mayReadFromMemory()))
LastStore = nullptr;

15
test/Transforms/EarlyCSE/readnone-mayunwind.ll Normal file
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@ -0,0 +1,15 @@
; RUN: opt -S -early-cse < %s | FileCheck %s
declare void @readnone_may_unwind() readnone
define void @f(i32* %ptr) {
; CHECK-LABEL: @f(
; CHECK: store i32 100, i32* %ptr
; CHECK: call void @readnone_may_unwind()
; CHECK: store i32 200, i32* %ptr
store i32 100, i32* %ptr
call void @readnone_may_unwind()
store i32 200, i32* %ptr
ret void
}