Disable r91104 for x86. It causes partial register stall which pessimize code in 32-bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91223 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 87f6fc0..e580772 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -1058,7 +1058,7 @@
return false;
}
-/// convertToThreeAddressWithLEA - Helper for convertToThreeAddress when 16-bit
+/// convertToThreeAddressWithLEA - Helper for convertToThreeAddress when
/// 16-bit LEA is disabled, use 32-bit LEA to form 3-address code by promoting
/// to a 32-bit superregister and then truncating back down to a 16-bit
/// subregister.
@@ -1081,11 +1081,11 @@
// Build and insert into an implicit UNDEF value. This is OK because
// well be shifting and then extracting the lower 16-bits.
- // This has the potential to cause partial stall. e.g.
+ // This has the potential to cause partial register stall. e.g.
// movw (%rbp,%rcx,2), %dx
// leal -65(%rdx), %esi
- // But testing has shown this *does* help performance (at least on modern
- // x86 machines).
+ // But testing has shown this *does* help performance in 64-bit mode (at
+ // least on modern x86 machines).
BuildMI(*MFI, MBBI, MI->getDebugLoc(), get(X86::IMPLICIT_DEF), leaInReg);
MachineInstr *InsMI =
BuildMI(*MFI, MBBI, MI->getDebugLoc(), get(X86::INSERT_SUBREG),leaInReg)
@@ -1189,7 +1189,9 @@
MachineInstr *NewMI = NULL;
// FIXME: 16-bit LEA's are really slow on Athlons, but not bad on P4's. When
// we have better subtarget support, enable the 16-bit LEA generation here.
+ // 16-bit LEA is also slow on Core2.
bool DisableLEA16 = true;
+ bool is64Bit = TM.getSubtarget<X86Subtarget>().is64Bit();
unsigned MIOpc = MI->getOpcode();
switch (MIOpc) {
@@ -1228,8 +1230,7 @@
unsigned ShAmt = MI->getOperand(2).getImm();
if (ShAmt == 0 || ShAmt >= 4) return 0;
- unsigned Opc = TM.getSubtarget<X86Subtarget>().is64Bit() ?
- X86::LEA64_32r : X86::LEA32r;
+ unsigned Opc = is64Bit ? X86::LEA64_32r : X86::LEA32r;
NewMI = BuildMI(MF, MI->getDebugLoc(), get(Opc))
.addReg(Dest, RegState::Define | getDeadRegState(isDead))
.addReg(0).addImm(1 << ShAmt)
@@ -1244,7 +1245,7 @@
if (ShAmt == 0 || ShAmt >= 4) return 0;
if (DisableLEA16)
- return convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV);
+ return is64Bit ? convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV) : 0;
NewMI = BuildMI(MF, MI->getDebugLoc(), get(X86::LEA16r))
.addReg(Dest, RegState::Define | getDeadRegState(isDead))
.addReg(0).addImm(1 << ShAmt)
@@ -1259,7 +1260,6 @@
if (hasLiveCondCodeDef(MI))
return 0;
- bool is64Bit = TM.getSubtarget<X86Subtarget>().is64Bit();
switch (MIOpc) {
default: return 0;
case X86::INC64r:
@@ -1277,7 +1277,7 @@
case X86::INC16r:
case X86::INC64_16r:
if (DisableLEA16)
- return convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV);
+ return is64Bit ? convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV) : 0;
assert(MI->getNumOperands() >= 2 && "Unknown inc instruction!");
NewMI = addRegOffset(BuildMI(MF, MI->getDebugLoc(), get(X86::LEA16r))
.addReg(Dest, RegState::Define |
@@ -1299,7 +1299,7 @@
case X86::DEC16r:
case X86::DEC64_16r:
if (DisableLEA16)
- return convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV);
+ return is64Bit ? convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV) : 0;
assert(MI->getNumOperands() >= 2 && "Unknown dec instruction!");
NewMI = addRegOffset(BuildMI(MF, MI->getDebugLoc(), get(X86::LEA16r))
.addReg(Dest, RegState::Define |
@@ -1323,7 +1323,7 @@
}
case X86::ADD16rr: {
if (DisableLEA16)
- return convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV);
+ return is64Bit ? convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV) : 0;
assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
unsigned Src2 = MI->getOperand(2).getReg();
bool isKill2 = MI->getOperand(2).isKill();
@@ -1356,7 +1356,7 @@
case X86::ADD16ri:
case X86::ADD16ri8:
if (DisableLEA16)
- return convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV);
+ return is64Bit ? convertToThreeAddressWithLEA(MIOpc, MFI, MBBI, LV) : 0;
assert(MI->getNumOperands() >= 3 && "Unknown add instruction!");
NewMI = addLeaRegOffset(BuildMI(MF, MI->getDebugLoc(), get(X86::LEA16r))
.addReg(Dest, RegState::Define |