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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
28 lines
1.1 KiB
LLVM
28 lines
1.1 KiB
LLVM
; RUN: llc -mtriple=aarch64-none-linux-gnu -aarch64-atomic-cfg-tidy=0 -verify-machineinstrs < %s | FileCheck %s
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; RUN: llc -code-model=large -mtriple=aarch64-none-linux-gnu -aarch64-atomic-cfg-tidy=0 -verify-machineinstrs < %s | FileCheck --check-prefix=CHECK-LARGE %s
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@addr = global i8* null
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define void @test_blockaddress() {
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; CHECK-LABEL: test_blockaddress:
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store volatile i8* blockaddress(@test_blockaddress, %block), i8** @addr
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%val = load volatile i8** @addr
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indirectbr i8* %val, [label %block]
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; CHECK: adrp [[DEST_HI:x[0-9]+]], [[DEST_LBL:.Ltmp[0-9]+]]
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; CHECK: add [[DEST:x[0-9]+]], [[DEST_HI]], {{#?}}:lo12:[[DEST_LBL]]
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; CHECK: str [[DEST]],
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; CHECK: ldr [[NEWDEST:x[0-9]+]]
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; CHECK: br [[NEWDEST]]
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; CHECK-LARGE: movz [[ADDR_REG:x[0-9]+]], #:abs_g3:[[DEST_LBL:.Ltmp[0-9]+]]
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; CHECK-LARGE: movk [[ADDR_REG]], #:abs_g2_nc:[[DEST_LBL]]
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; CHECK-LARGE: movk [[ADDR_REG]], #:abs_g1_nc:[[DEST_LBL]]
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; CHECK-LARGE: movk [[ADDR_REG]], #:abs_g0_nc:[[DEST_LBL]]
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; CHECK-LARGE: str [[ADDR_REG]],
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; CHECK-LARGE: ldr [[NEWDEST:x[0-9]+]]
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; CHECK-LARGE: br [[NEWDEST]]
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block:
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ret void
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}
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