From 9b8c67443280c8e1b50766b312a5c07df080a638 Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Tue, 17 Jul 2007 21:26:42 +0000 Subject: [PATCH] Fold prologue esp update when possible. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39984 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/X86RegisterInfo.cpp | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp index 9278516d05e..da65db03e4b 100644 --- a/lib/Target/X86/X86RegisterInfo.cpp +++ b/lib/Target/X86/X86RegisterInfo.cpp @@ -1236,7 +1236,28 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { MBB.insert(MBBI, MI); } } else { - emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII); + // If there is an ADD32ri or SUB32ri of ESP immediately after this + // instruction, merge the two instructions. + if (MBBI != MBB.end()) { + MachineBasicBlock::iterator NI = next(MBBI); + unsigned Opc = MBBI->getOpcode(); + if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 || + Opc == X86::ADD32ri || Opc == X86::ADD32ri8) && + MBBI->getOperand(0).getReg() == StackPtr) { + NumBytes -= MBBI->getOperand(2).getImm(); + MBB.erase(MBBI); + MBBI = NI; + } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 || + Opc == X86::SUB32ri || Opc == X86::SUB32ri8) && + MBBI->getOperand(0).getReg() == StackPtr) { + NumBytes += MBBI->getOperand(2).getImm(); + MBB.erase(MBBI); + MBBI = NI; + } + } + + if (NumBytes) + emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII); } }