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[AArch64] Fix over-eager early-exit in load-store combiner 

Fix early-exit analysis for memory operation pairing when operations are
not emitted in ascending order.

Reviewers: mcrosier, t.p.northover

Subscribers: aemerson, rengolin, llvm-commits

Differential Revision: https://reviews.llvm.org/D28251

llvm-svn: 291008
This commit is contained in:
Nirav Dave 2017-01-04 21:21:46 +00:00
parent 6e2207a134
commit 0f9d111f97
2 changed files with 15 additions and 0 deletions
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3
llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
View File

@ -1470,6 +1470,9 @@ bool AArch64LoadStoreOpt::tryToPairLdStInst(MachineBasicBlock::iterator &MBBI) {
bool IsUnscaled = TII->isUnscaledLdSt(MI);
int Offset = getLdStOffsetOp(MI).getImm();
int OffsetStride = IsUnscaled ? getMemScale(MI) : 1;
// Allow one more for offset.
if (Offset > 0)
Offset -= OffsetStride;
if (!inBoundsForPair(IsUnscaled, Offset, OffsetStride))
return false;

12
llvm/test/CodeGen/AArch64/store_merge_pair_offset.ll Normal file
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@ -0,0 +1,12 @@
; RUN: llc -mtriple=aarch64-linux-gnu -aarch64-enable-atomic-cfg-tidy=0 -disable-lsr -verify-machineinstrs -enable-misched=false -enable-post-misched=false -o - %s | FileCheck %s
define i64 @test(i64* %a) nounwind {
; CHECK: ldp x{{[0-9]+}}, x{{[0-9]+}}
; CHECK-NOT: ldr
%p1 = getelementptr inbounds i64, i64* %a, i32 64
%tmp1 = load i64, i64* %p1, align 2
%p2 = getelementptr inbounds i64, i64* %a, i32 63
%tmp2 = load i64, i64* %p2, align 2
%tmp3 = add i64 %tmp1, %tmp2
ret i64 %tmp3
}