diff options
author | Lang Hames <lhames@gmail.com> | 2014-12-02 21:36:24 +0000 |
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committer | Lang Hames <lhames@gmail.com> | 2014-12-02 21:36:24 +0000 |
commit | 26cc5bea3921f373be326e750bffd9f9a6d23313 (patch) | |
tree | 835e05ff20746300c5f48859e8930d41b0568d6c /lib/Target/AArch64/AArch64AsmPrinter.cpp | |
parent | d90fc9d0fc5412ec3b57d3a949cd8d875a740b54 (diff) |
[AArch64][Stackmaps] Optimize stackmap shadows on AArch64.
Reduce the number of nops emitted for stackmap shadows on AArch64 by counting
non-stackmap instructions up to the next branch target towards the requested
shadow.
<rdar://problem/14959522>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223156 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/AArch64/AArch64AsmPrinter.cpp')
-rw-r--r-- | lib/Target/AArch64/AArch64AsmPrinter.cpp | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/lib/Target/AArch64/AArch64AsmPrinter.cpp b/lib/Target/AArch64/AArch64AsmPrinter.cpp index 8bee4f51351..08ee687d84a 100644 --- a/lib/Target/AArch64/AArch64AsmPrinter.cpp +++ b/lib/Target/AArch64/AArch64AsmPrinter.cpp @@ -381,8 +381,23 @@ void AArch64AsmPrinter::LowerSTACKMAP(MCStreamer &OutStreamer, StackMaps &SM, unsigned NumNOPBytes = MI.getOperand(1).getImm(); SM.recordStackMap(MI); - // Emit padding. assert(NumNOPBytes % 4 == 0 && "Invalid number of NOP bytes requested!"); + + // Scan ahead to trim the shadow. + const MachineBasicBlock &MBB = *MI.getParent(); + MachineBasicBlock::const_iterator MII(MI); + ++MII; + while (NumNOPBytes > 0) { + if (MII == MBB.end() || MII->isCall() || + MII->getOpcode() == AArch64::DBG_VALUE || + MII->getOpcode() == TargetOpcode::PATCHPOINT || + MII->getOpcode() == TargetOpcode::STACKMAP) + break; + ++MII; + NumNOPBytes -= 4; + } + + // Emit nops. for (unsigned i = 0; i < NumNOPBytes; i += 4) EmitToStreamer(OutStreamer, MCInstBuilder(AArch64::HINT).addImm(0)); } |