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3bb84c9bcc
The C and C++ semantics for compare_exchange require it to return a bool
indicating success. This gets mapped to LLVM IR which follows each cmpxchg with
an icmp of the value loaded against the desired value.
When lowered to ldxr/stxr loops, this extra comparison is redundant: its
results are implicit in the control-flow of the function.
This commit makes two changes: it replaces that icmp with appropriate PHI
nodes, and then makes sure earlyCSE is called after expansion to actually make
use of the opportunities revealed.
I've also added -{arm,aarch64}-enable-atomic-tidy options, so that
existing fragile tests aren't perturbed too much by the change. Many
of them either rely on undef/unreachable too pervasively to be
restored to something well-defined (particularly while making sure
they test the same obscure assert from many years ago), or depend on a
particular CFG shape, which is disrupted by SimplifyCFG.
rdar://problem/16227836
llvm-svn: 209883
75 lines
1.8 KiB
LLVM
75 lines
1.8 KiB
LLVM
; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mattr=+thumb2 -arm-atomic-cfg-tidy=0 | FileCheck %s
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; If-conversion defeats the purpose of this test, which is to check
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; conditional branch generation, so a call to make sure it doesn't
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; happen and we get actual branches.
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declare void @foo()
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define i32 @f1(i32 %a, i32 %b, i32* %v) {
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entry:
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; CHECK-LABEL: f1:
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; CHECK: bne LBB
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%tmp = icmp eq i32 %a, %b ; <i1> [#uses=1]
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br i1 %tmp, label %cond_true, label %return
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cond_true: ; preds = %entry
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call void @foo()
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store i32 0, i32* %v
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ret i32 0
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return: ; preds = %entry
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call void @foo()
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ret i32 1
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}
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define i32 @f2(i32 %a, i32 %b, i32* %v) {
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entry:
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; CHECK-LABEL: f2:
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; CHECK: bge LBB
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%tmp = icmp slt i32 %a, %b ; <i1> [#uses=1]
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br i1 %tmp, label %cond_true, label %return
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cond_true: ; preds = %entry
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call void @foo()
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store i32 0, i32* %v
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ret i32 0
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return: ; preds = %entry
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call void @foo()
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ret i32 1
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}
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define i32 @f3(i32 %a, i32 %b, i32* %v) {
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entry:
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; CHECK-LABEL: f3:
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; CHECK: bhs LBB
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%tmp = icmp ult i32 %a, %b ; <i1> [#uses=1]
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br i1 %tmp, label %cond_true, label %return
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cond_true: ; preds = %entry
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call void @foo()
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store i32 0, i32* %v
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ret i32 0
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return: ; preds = %entry
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call void @foo()
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ret i32 1
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}
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define i32 @f4(i32 %a, i32 %b, i32* %v) {
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entry:
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; CHECK-LABEL: f4:
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; CHECK: blo LBB
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%tmp = icmp uge i32 %a, %b ; <i1> [#uses=1]
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br i1 %tmp, label %cond_true, label %return
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cond_true: ; preds = %entry
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call void @foo()
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store i32 0, i32* %v
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ret i32 0
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return: ; preds = %entry
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call void @foo()
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ret i32 1
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}
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