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X86 Peephole: fold loads to the source register operand if possible.

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Add more comments and use early returns to reduce nesting in isLoadFoldable.
Also disable folding for V_SET0 to avoid introducing a const pool entry and
a const pool load.

rdar://10554090 and rdar://11873276

llvm-svn: 161207
This commit is contained in:
Manman Ren 2012-08-02 19:37:32 +00:00
parent 6c18ae4d14
commit 2c236a30f6
5 changed files with 67 additions and 38 deletions
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6
include/llvm/Target/TargetInstrInfo.h
View File

@ -696,7 +696,11 @@ public:
/// optimizeLoadInstr - Try to remove the load by folding it to a register
/// operand at the use. We fold the load instructions if and only if the
/// def and use are in the same BB.
/// def and use are in the same BB. We only look at one load and see
/// whether it can be folded into MI. FoldAsLoadDefReg is the virtual register
/// defined by the load we are trying to fold. DefMI returns the machine
/// instruction that defines FoldAsLoadDefReg, and the function returns
/// the machine instruction generated due to folding.
virtual MachineInstr* optimizeLoadInstr(MachineInstr *MI,
const MachineRegisterInfo *MRI,
unsigned &FoldAsLoadDefReg,

29
lib/CodeGen/PeepholeOptimizer.cpp
View File

@ -391,20 +391,21 @@ bool PeepholeOptimizer::optimizeCmpInstr(MachineInstr *MI,
/// register defined has a single use.
bool PeepholeOptimizer::isLoadFoldable(MachineInstr *MI,
unsigned &FoldAsLoadDefReg) {
if (MI->canFoldAsLoad()) {
const MCInstrDesc &MCID = MI->getDesc();
if (MCID.getNumDefs() == 1) {
unsigned Reg = MI->getOperand(0).getReg();
// To reduce compilation time, we check MRI->hasOneUse when inserting
// loads. It should be checked when processing uses of the load, since
// uses can be removed during peephole.
if (!MI->getOperand(0).getSubReg() &&
TargetRegisterInfo::isVirtualRegister(Reg) &&
MRI->hasOneUse(Reg)) {
FoldAsLoadDefReg = Reg;
return true;
}
}
if (!MI->canFoldAsLoad() || !MI->mayLoad())
return false;
const MCInstrDesc &MCID = MI->getDesc();
if (MCID.getNumDefs() != 1)
return false;
unsigned Reg = MI->getOperand(0).getReg();
// To reduce compilation time, we check MRI->hasOneUse when inserting
// loads. It should be checked when processing uses of the load, since
// uses can be removed during peephole.
if (!MI->getOperand(0).getSubReg() &&
TargetRegisterInfo::isVirtualRegister(Reg) &&
MRI->hasOneUse(Reg)) {
FoldAsLoadDefReg = Reg;
return true;
}
return false;
}

6
lib/Target/X86/X86InstrInfo.h
View File

@ -389,7 +389,11 @@ public:
/// optimizeLoadInstr - Try to remove the load by folding it to a register
/// operand at the use. We fold the load instructions if and only if the
/// def and use are in the same BB.
/// def and use are in the same BB. We only look at one load and see
/// whether it can be folded into MI. FoldAsLoadDefReg is the virtual register
/// defined by the load we are trying to fold. DefMI returns the machine
/// instruction that defines FoldAsLoadDefReg, and the function returns
/// the machine instruction generated due to folding.
virtual MachineInstr* optimizeLoadInstr(MachineInstr *MI,
const MachineRegisterInfo *MRI,
unsigned &FoldAsLoadDefReg,

60
test/CodeGen/X86/sse-minmax.ll
View File

@ -137,13 +137,16 @@ define double @ole_inverse(double %x, double %y) nounwind {
}
; CHECK: ogt_x:
; CHECK-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; CHECK-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; CHECK-NEXT: maxsd %xmm1, %xmm0
; CHECK-NEXT: ret
; UNSAFE: ogt_x:
; UNSAFE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: maxsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: ogt_x:
; FINITE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: maxsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @ogt_x(double %x) nounwind {
%c = fcmp ogt double %x, 0.000000e+00
@ -152,13 +155,16 @@ define double @ogt_x(double %x) nounwind {
}
; CHECK: olt_x:
; CHECK-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; CHECK-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; CHECK-NEXT: minsd %xmm1, %xmm0
; CHECK-NEXT: ret
; UNSAFE: olt_x:
; UNSAFE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: minsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: olt_x:
; FINITE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: minsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @olt_x(double %x) nounwind {
%c = fcmp olt double %x, 0.000000e+00
@ -211,10 +217,12 @@ define double @olt_inverse_x(double %x) nounwind {
; CHECK: oge_x:
; CHECK: ucomisd %xmm1, %xmm0
; UNSAFE: oge_x:
; UNSAFE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: maxsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: oge_x:
; FINITE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: maxsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @oge_x(double %x) nounwind {
%c = fcmp oge double %x, 0.000000e+00
@ -225,10 +233,12 @@ define double @oge_x(double %x) nounwind {
; CHECK: ole_x:
; CHECK: ucomisd %xmm0, %xmm1
; UNSAFE: ole_x:
; UNSAFE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: minsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: ole_x:
; FINITE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: minsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @ole_x(double %x) nounwind {
%c = fcmp ole double %x, 0.000000e+00
@ -401,10 +411,12 @@ define double @ule_inverse(double %x, double %y) nounwind {
; CHECK: ugt_x:
; CHECK: ucomisd %xmm0, %xmm1
; UNSAFE: ugt_x:
; UNSAFE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: maxsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: ugt_x:
; FINITE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: maxsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @ugt_x(double %x) nounwind {
%c = fcmp ugt double %x, 0.000000e+00
@ -415,10 +427,12 @@ define double @ugt_x(double %x) nounwind {
; CHECK: ult_x:
; CHECK: ucomisd %xmm1, %xmm0
; UNSAFE: ult_x:
; UNSAFE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: minsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: ult_x:
; FINITE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: minsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @ult_x(double %x) nounwind {
%c = fcmp ult double %x, 0.000000e+00
@ -468,10 +482,12 @@ define double @ult_inverse_x(double %x) nounwind {
; CHECK-NEXT: movap{{[sd]}} %xmm1, %xmm0
; CHECK-NEXT: ret
; UNSAFE: uge_x:
; UNSAFE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: maxsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: uge_x:
; FINITE-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: maxsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @uge_x(double %x) nounwind {
%c = fcmp uge double %x, 0.000000e+00
@ -485,10 +501,12 @@ define double @uge_x(double %x) nounwind {
; CHECK-NEXT: movap{{[sd]}} %xmm1, %xmm0
; CHECK-NEXT: ret
; UNSAFE: ule_x:
; UNSAFE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; UNSAFE-NEXT: minsd %xmm1, %xmm0
; UNSAFE-NEXT: ret
; FINITE: ule_x:
; FINITE-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; FINITE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; FINITE-NEXT: minsd %xmm1, %xmm0
; FINITE-NEXT: ret
define double @ule_x(double %x) nounwind {
%c = fcmp ule double %x, 0.000000e+00
@ -497,7 +515,8 @@ define double @ule_x(double %x) nounwind {
}
; CHECK: uge_inverse_x:
; CHECK-NEXT: minsd LCP{{.*}}(%rip), %xmm0
; CHECK-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; CHECK-NEXT: minsd %xmm1, %xmm0
; CHECK-NEXT: ret
; UNSAFE: uge_inverse_x:
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1
@ -516,7 +535,8 @@ define double @uge_inverse_x(double %x) nounwind {
}
; CHECK: ule_inverse_x:
; CHECK-NEXT: maxsd LCP{{.*}}(%rip), %xmm0
; CHECK-NEXT: xorp{{[sd]}} %xmm1, %xmm1
; CHECK-NEXT: maxsd %xmm1, %xmm0
; CHECK-NEXT: ret
; UNSAFE: ule_inverse_x:
; UNSAFE-NEXT: xorp{{[sd]}} %xmm1, %xmm1

4
test/CodeGen/X86/vec_compare.ll
View File

@ -14,8 +14,8 @@ define <4 x i32> @test1(<4 x i32> %A, <4 x i32> %B) nounwind {
define <4 x i32> @test2(<4 x i32> %A, <4 x i32> %B) nounwind {
; CHECK: test2:
; CHECK: pcmp
; CHECK: pxor LCP
; CHECK: movdqa
; CHECK: pcmp
; CHECK: pxor
; CHECK: ret
%C = icmp sge <4 x i32> %A, %B
%D = sext <4 x i1> %C to <4 x i32>