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-rw-r--r--lib/Target/X86/X86FixupLEAs.cpp107
1 files changed, 93 insertions, 14 deletions
diff --git a/lib/Target/X86/X86FixupLEAs.cpp b/lib/Target/X86/X86FixupLEAs.cpp
index c2c234be8c..6c5b86f619 100644
--- a/lib/Target/X86/X86FixupLEAs.cpp
+++ b/lib/Target/X86/X86FixupLEAs.cpp
@@ -13,7 +13,6 @@
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "x86-fixup-LEAs"
#include "X86.h"
#include "X86InstrInfo.h"
#include "X86Subtarget.h"
@@ -28,6 +27,8 @@
#include "llvm/Target/TargetInstrInfo.h"
using namespace llvm;
+#define DEBUG_TYPE "x86-fixup-LEAs"
+
STATISTIC(NumLEAs, "Number of LEA instructions created");
namespace {
@@ -56,6 +57,11 @@ namespace {
void processInstruction(MachineBasicBlock::iterator& I,
MachineFunction::iterator MFI);
+ /// \brief Given a LEA instruction which is unprofitable
+ /// on Silvermont try to replace it with an equivalent ADD instruction
+ void processInstructionForSLM(MachineBasicBlock::iterator& I,
+ MachineFunction::iterator MFI);
+
/// \brief Determine if an instruction references a machine register
/// and, if so, whether it reads or writes the register.
RegUsageState usesRegister(MachineOperand& p,
@@ -85,7 +91,7 @@ namespace {
private:
MachineFunction *MF;
const TargetMachine *TM;
- const TargetInstrInfo *TII; // Machine instruction info.
+ const X86InstrInfo *TII; // Machine instruction info.
};
char FixupLEAPass::ID = 0;
@@ -97,7 +103,7 @@ FixupLEAPass::postRAConvertToLEA(MachineFunction::iterator &MFI,
MachineInstr* MI = MBBI;
MachineInstr* NewMI;
switch (MI->getOpcode()) {
- case X86::MOV32rr:
+ case X86::MOV32rr:
case X86::MOV64rr: {
const MachineOperand& Src = MI->getOperand(1);
const MachineOperand& Dest = MI->getOperand(0);
@@ -123,7 +129,7 @@ FixupLEAPass::postRAConvertToLEA(MachineFunction::iterator &MFI,
if (!MI->getOperand(2).isImm()) {
// convertToThreeAddress will call getImm()
// which requires isImm() to be true
- return 0;
+ return nullptr;
}
break;
case X86::ADD16rr:
@@ -132,10 +138,10 @@ FixupLEAPass::postRAConvertToLEA(MachineFunction::iterator &MFI,
// if src1 != src2, then convertToThreeAddress will
// need to create a Virtual register, which we cannot do
// after register allocation.
- return 0;
+ return nullptr;
}
}
- return TII->convertToThreeAddress(MFI, MBBI, 0);
+ return TII->convertToThreeAddress(MFI, MBBI, nullptr);
}
FunctionPass *llvm::createX86FixupLEAs() {
@@ -143,9 +149,12 @@ FunctionPass *llvm::createX86FixupLEAs() {
}
bool FixupLEAPass::runOnMachineFunction(MachineFunction &Func) {
- MF = &Func;
- TM = &MF->getTarget();
- TII = TM->getInstrInfo();
+ TM = &Func.getTarget();
+ const X86Subtarget &ST = TM->getSubtarget<X86Subtarget>();
+ if (!ST.LEAusesAG() && !ST.slowLEA())
+ return false;
+
+ TII = static_cast<const X86InstrInfo*>(TM->getInstrInfo());
DEBUG(dbgs() << "Start X86FixupLEAs\n";);
// Process all basic blocks.
@@ -211,7 +220,7 @@ MachineBasicBlock::iterator FixupLEAPass::searchBackwards(MachineOperand& p,
InstrDistance += TII->getInstrLatency(TM->getInstrItineraryData(), CurInst);
Found = getPreviousInstr(CurInst, MFI);
}
- return 0;
+ return nullptr;
}
void FixupLEAPass::processInstruction(MachineBasicBlock::iterator& I,
@@ -242,9 +251,9 @@ void FixupLEAPass::seekLEAFixup(MachineOperand& p,
MachineInstr* NewMI = postRAConvertToLEA(MFI, MBI);
if (NewMI) {
++NumLEAs;
- DEBUG(dbgs() << "Candidate to replace:"; MBI->dump(););
+ DEBUG(dbgs() << "FixLEA: Candidate to replace:"; MBI->dump(););
// now to replace with an equivalent LEA...
- DEBUG(dbgs() << "Replaced by: "; NewMI->dump(););
+ DEBUG(dbgs() << "FixLEA: Replaced by: "; NewMI->dump(););
MFI->erase(MBI);
MachineBasicBlock::iterator J =
static_cast<MachineBasicBlock::iterator> (NewMI);
@@ -253,10 +262,80 @@ void FixupLEAPass::seekLEAFixup(MachineOperand& p,
}
}
+void FixupLEAPass::processInstructionForSLM(MachineBasicBlock::iterator &I,
+ MachineFunction::iterator MFI) {
+ MachineInstr *MI = I;
+ const int opcode = MI->getOpcode();
+ if (opcode != X86::LEA16r && opcode != X86::LEA32r && opcode != X86::LEA64r &&
+ opcode != X86::LEA64_32r)
+ return;
+ if (MI->getOperand(5).getReg() != 0 || !MI->getOperand(4).isImm() ||
+ !TII->isSafeToClobberEFLAGS(*MFI, I))
+ return;
+ const unsigned DstR = MI->getOperand(0).getReg();
+ const unsigned SrcR1 = MI->getOperand(1).getReg();
+ const unsigned SrcR2 = MI->getOperand(3).getReg();
+ if ((SrcR1 == 0 || SrcR1 != DstR) && (SrcR2 == 0 || SrcR2 != DstR))
+ return;
+ if (MI->getOperand(2).getImm() > 1)
+ return;
+ int addrr_opcode, addri_opcode;
+ switch (opcode) {
+ case X86::LEA16r:
+ addrr_opcode = X86::ADD16rr;
+ addri_opcode = X86::ADD16ri;
+ break;
+ case X86::LEA32r:
+ addrr_opcode = X86::ADD32rr;
+ addri_opcode = X86::ADD32ri;
+ break;
+ case X86::LEA64_32r:
+ case X86::LEA64r:
+ addrr_opcode = X86::ADD64rr;
+ addri_opcode = X86::ADD64ri32;
+ break;
+ default:
+ assert(false && "Unexpected LEA instruction");
+ }
+ DEBUG(dbgs() << "FixLEA: Candidate to replace:"; I->dump(););
+ DEBUG(dbgs() << "FixLEA: Replaced by: ";);
+ MachineInstr *NewMI = 0;
+ const MachineOperand &Dst = MI->getOperand(0);
+ // Make ADD instruction for two registers writing to LEA's destination
+ if (SrcR1 != 0 && SrcR2 != 0) {
+ const MachineOperand &Src1 = MI->getOperand(SrcR1 == DstR ? 1 : 3);
+ const MachineOperand &Src2 = MI->getOperand(SrcR1 == DstR ? 3 : 1);
+ NewMI = BuildMI(*MF, MI->getDebugLoc(), TII->get(addrr_opcode))
+ .addOperand(Dst)
+ .addOperand(Src1)
+ .addOperand(Src2);
+ MFI->insert(I, NewMI);
+ DEBUG(NewMI->dump(););
+ }
+ // Make ADD instruction for immediate
+ if (MI->getOperand(4).getImm() != 0) {
+ const MachineOperand &SrcR = MI->getOperand(SrcR1 == DstR ? 1 : 3);
+ NewMI = BuildMI(*MF, MI->getDebugLoc(), TII->get(addri_opcode))
+ .addOperand(Dst)
+ .addOperand(SrcR)
+ .addImm(MI->getOperand(4).getImm());
+ MFI->insert(I, NewMI);
+ DEBUG(NewMI->dump(););
+ }
+ if (NewMI) {
+ MFI->erase(I);
+ I = static_cast<MachineBasicBlock::iterator>(NewMI);
+ }
+}
+
bool FixupLEAPass::processBasicBlock(MachineFunction &MF,
MachineFunction::iterator MFI) {
- for (MachineBasicBlock::iterator I = MFI->begin(); I != MFI->end(); ++I)
- processInstruction(I, MFI);
+ for (MachineBasicBlock::iterator I = MFI->begin(); I != MFI->end(); ++I) {
+ if (TM->getSubtarget<X86Subtarget>().isSLM())
+ processInstructionForSLM(I, MFI);
+ else
+ processInstruction(I, MFI);
+ }
return false;
}
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