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MachineInstrBundle: Fix reversed isSuperRegisterEq() call 

Unfortunately this fix had the effect of exposing the
-verify-machineinstrs FIXME of X86InstrInfo.cpp in two testcases for
which I disabled it for now.
Two testcases also have additional pushq/popq where the corrected code
cannot prove that %rax is dead any longer. Looking at the examples, this
could potentially be fixed by improving computeRegisterLiveness() to check
the live-in lists of the successors blocks when reaching the end of a
block.

This fixes http://llvm.org/PR25951.

llvm-svn: 256799
This commit is contained in:
Matthias Braun 2016-01-05 00:45:35 +00:00
parent d84af9ba8b
commit 7e762e4f9c
4 changed files with 25 additions and 11 deletions
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2
llvm/lib/CodeGen/MachineInstrBundle.cpp
View File

@ -315,7 +315,7 @@ MachineOperandIteratorBase::analyzePhysReg(unsigned Reg,
if (!TRI->regsOverlap(MOReg, Reg))
continue;
bool Covered = TRI->isSuperRegisterEq(MOReg, Reg);
bool Covered = TRI->isSuperRegisterEq(Reg, MOReg);
if (MO.readsReg()) {
PRI.Read = true;
if (Covered) {

4
llvm/lib/Target/X86/X86InstrInfo.cpp
View File

@ -4466,6 +4466,10 @@ void X86InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
// (unnecessarily) saving+restoring a dead register. However the
// MachineVerifier expects operands that read from dead registers
// to be marked with the "undef" flag.
// An example of this can be found in
// test/CodeGen/X86/peephole-na-phys-copy-folding.ll and
// test/CodeGen/X86/cmpxchg-clobber-flags.ll when using
// -verify-machineinstrs.
BuildMI(MBB, MI, DL, get(Push)).addReg(AX, getKillRegState(true));
}
if (FromEFLAGS) {

23
llvm/test/CodeGen/X86/cmpxchg-clobber-flags.ll
View File

@ -1,11 +1,14 @@
; RUN: llc -verify-machineinstrs -mtriple=i386-linux-gnu %s -o - | FileCheck %s -check-prefix=i386
; RUN: llc -verify-machineinstrs -mtriple=i386-linux-gnu -pre-RA-sched=fast %s -o - | FileCheck %s -check-prefix=i386f
; RUN: llc -mtriple=i386-linux-gnu %s -o - | FileCheck %s -check-prefix=i386
; RUN: llc -mtriple=i386-linux-gnu -pre-RA-sched=fast %s -o - | FileCheck %s -check-prefix=i386f
; RUN: llc -verify-machineinstrs -mtriple=x86_64-linux-gnu %s -o - | FileCheck %s -check-prefix=x8664
; RUN: llc -verify-machineinstrs -mtriple=x86_64-linux-gnu -pre-RA-sched=fast %s -o - | FileCheck %s -check-prefix=x8664
; RUN: llc -verify-machineinstrs -mtriple=x86_64-linux-gnu -mattr=+sahf %s -o - | FileCheck %s -check-prefix=x8664-sahf
; RUN: llc -verify-machineinstrs -mtriple=x86_64-linux-gnu -mattr=+sahf -pre-RA-sched=fast %s -o - | FileCheck %s -check-prefix=x8664-sahf
; RUN: llc -verify-machineinstrs -mtriple=x86_64-linux-gnu -mcpu=corei7 %s -o - | FileCheck %s -check-prefix=x8664-sahf
; RUN: llc -mtriple=x86_64-linux-gnu %s -o - | FileCheck %s -check-prefix=x8664
; RUN: llc -mtriple=x86_64-linux-gnu -pre-RA-sched=fast %s -o - | FileCheck %s -check-prefix=x8664
; RUN: llc -mtriple=x86_64-linux-gnu -mattr=+sahf %s -o - | FileCheck %s -check-prefix=x8664-sahf
; RUN: llc -mtriple=x86_64-linux-gnu -mattr=+sahf -pre-RA-sched=fast %s -o - | FileCheck %s -check-prefix=x8664-sahf
; RUN: llc -mtriple=x86_64-linux-gnu -mcpu=corei7 %s -o - | FileCheck %s -check-prefix=x8664-sahf
; TODO: Reenable verify-machineinstr once the if (!AXDead) // FIXME
; in X86InstrInfo::copyPhysReg() is resolved.
declare i32 @foo()
declare i32 @bar(i64)
@ -58,9 +61,11 @@ define i64 @test_intervening_call(i64* %foo, i64 %bar, i64 %baz) {
; x8664-sahf-NEXT: popq %rax
; x8664-sahf-NEXT: movq %rax, %rdi
; x8664-sahf-NEXT: callq bar
; x8664-sahf-NEXT: pushq %rax
; x8664-sahf-NEXT: movq [[FLAGS]], %rax
; x8664-sahf-NEXT: addb $127, %al
; x8664-sahf-NEXT: sahf
; x8664-sahf-NEXT: popq %rax
; x8664-sahf-NEXT: jne
%cx = cmpxchg i64* %foo, i64 %bar, i64 %baz seq_cst seq_cst
@ -161,9 +166,11 @@ define i32 @test_feed_cmov(i32* %addr, i32 %desired, i32 %new) {
; x8664-sahf-LABEL: test_feed_cmov:
; x8664-sahf: cmpxchgl
; x8664-sahf: seto %al
; x8664-sahf: pushq %rax
; x8664-sahf-NEXT: seto %al
; x8664-sahf-NEXT: lahf
; x8664-sahf-NEXT: movq %rax, [[FLAGS:%.*]]
; x8664-sahf-NEXT: popq %rax
; x8664-sahf-NEXT: callq foo
; x8664-sahf-NEXT: pushq %rax
; x8664-sahf-NEXT: movq [[FLAGS]], %rax

7
llvm/test/CodeGen/X86/peephole-na-phys-copy-folding.ll
View File

@ -1,5 +1,8 @@
; RUN: llc -verify-machineinstrs -mtriple=i386-linux-gnu %s -o - | FileCheck %s
; RUN: llc -verify-machineinstrs -mtriple=x86_64-linux-gnu -mattr=+sahf %s -o - | FileCheck %s
; RUN: llc -mtriple=i386-linux-gnu %s -o - | FileCheck %s
; RUN: llc -mtriple=x86_64-linux-gnu -mattr=+sahf %s -o - | FileCheck %s
; TODO: Reenable verify-machineinstrs once the if (!AXDead) // FIXME in
; X86InstrInfo::copyPhysReg() is resolved.
; The peephole optimizer can elide some physical register copies such as
; EFLAGS. Make sure the flags are used directly, instead of needlessly using