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[LICM] When promoting scalars, allow inserting stores to thread-local allocas.

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This is similar to the allocfn case - if an alloca is not captured, then it's
necessarily thread-local.

Differential Revision: https://reviews.llvm.org/D28170


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290738 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Kuperstein 2016-12-30 01:03:17 +00:00
parent ddd3bb716c
commit 4f67d55a96
2 changed files with 43 additions and 2 deletions
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3
lib/Transforms/Scalar/LICM.cpp
View File

@ -1034,7 +1034,8 @@ bool llvm::promoteLoopAccessesToScalars(
if (!SafeToInsertStore) {
Value *Object = GetUnderlyingObject(SomePtr, MDL);
SafeToInsertStore =
isAllocLikeFn(Object, TLI) && !PointerMayBeCaptured(Object, true, true);
(isAllocLikeFn(Object, TLI) || isa<AllocaInst>(Object)) &&
!PointerMayBeCaptured(Object, true, true);
}
// If we've still failed to prove we can sink the store, give up.

42
test/Transforms/LICM/promote-tls.ll
View File

@ -12,6 +12,7 @@ target triple = "x86_64-linux-generic"
declare i8* @malloc(i64)
; Exercise the TLS case
; CHECK-LABEL: @test
define i32* @test(i32 %n) {
entry:
;; ignore the required null check for simplicity
@ -49,9 +50,48 @@ for.cond.for.end_crit_edge: ; preds = %for.body
ret i32* null
}
; Stack allocations can also be thread-local
; CHECK-LABEL: @test2
define i32* @test2(i32 %n) {
entry:
%mem = alloca i8, i32 16
%addr = bitcast i8* %mem to i32*
br label %for.body.lr.ph
for.body.lr.ph: ; preds = %entry
br label %for.header
for.header:
%i.02 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
%old = load i32, i32* %addr, align 4
; deliberate impossible to analyze branch
%guard = load atomic i8*, i8** @p monotonic, align 8
%exitcmp = icmp eq i8* %guard, null
br i1 %exitcmp, label %for.body, label %early-exit
early-exit:
; CHECK-LABEL: early-exit:
; CHECK: store i32 %new1.lcssa, i32* %addr, align 1
ret i32* null
for.body:
%new = add i32 %old, 1
store i32 %new, i32* %addr, align 4
%inc = add nsw i32 %i.02, 1
%cmp = icmp slt i32 %inc, %n
br i1 %cmp, label %for.header, label %for.cond.for.end_crit_edge
for.cond.for.end_crit_edge: ; preds = %for.body
; CHECK-LABEL: for.cond.for.end_crit_edge:
; CHECK: store i32 %new.lcssa, i32* %addr, align 1
%split = phi i32* [ %addr, %for.body ]
ret i32* null
}
declare i8* @not_malloc(i64)
; Negative test - not TLS
; CHECK-LABEL: @test_neg
define i32* @test_neg(i32 %n) {
entry:
;; ignore the required null check for simplicity
@ -93,6 +133,7 @@ for.cond.for.end_crit_edge: ; preds = %for.body
; Negative test - can't speculate load since branch
; may control alignment
; CHECK-LABEL: @test_neg2
define i32* @test_neg2(i32 %n) {
entry:
;; ignore the required null check for simplicity
@ -131,4 +172,3 @@ for.cond.for.end_crit_edge: ; preds = %for.body
%split = phi i32* [ %addr, %for.body ]
ret i32* null
}