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[NFC][ARM] Comments and lambdas 

Add some comments in LowOverheadLoops and make some lambda variables
explicit arguments instead of capturing.
This commit is contained in:
Sam Parker 2020-09-29 08:41:53 +01:00
parent 98ef7e29b0
commit 4c19b89b25
1 changed files with 11 additions and 5 deletions
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16
llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp
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@ -921,14 +921,17 @@ void LowOverheadLoop::Validate(ARMBasicBlockUtils *BBUtils) {
if (Revert) if (Revert)
return; return;
auto ValidateRanges = [this, &BBUtils]() { // Check branch target ranges: WLS[TP] can only branch forwards and LE[TP]
// can only jump back.
auto ValidateRanges = [](MachineInstr *Start, MachineInstr *End,
ARMBasicBlockUtils *BBUtils, MachineLoop &ML) {
if (!End->getOperand(1).isMBB()) if (!End->getOperand(1).isMBB())
report_fatal_error("Expected LoopEnd to target basic block"); report_fatal_error("Expected LoopEnd to target basic block");
// TODO Maybe there's cases where the target doesn't have to be the header, // TODO Maybe there's cases where the target doesn't have to be the header,
// but for now be safe and revert. // but for now be safe and revert.
if (End->getOperand(1).getMBB() != ML.getHeader()) { if (End->getOperand(1).getMBB() != ML.getHeader()) {
LLVM_DEBUG(dbgs() << "ARM Loops: LoopEnd is not targetting header.\n"); LLVM_DEBUG(dbgs() << "ARM Loops: LoopEnd is not targeting header.\n");
return false; return false;
} }
@ -950,7 +953,10 @@ void LowOverheadLoop::Validate(ARMBasicBlockUtils *BBUtils) {
return true; return true;
}; };
auto FindStartInsertionPoint = [this]() -> MachineInstr* { // Find a suitable position to insert the loop start instruction. It needs to
// be able to safely define LR.
auto FindStartInsertionPoint = [](MachineInstr *Start,
ReachingDefAnalysis &RDA) -> MachineInstr* {
// We can define LR because LR already contains the same value. // We can define LR because LR already contains the same value.
if (Start->getOperand(0).getReg() == ARM::LR) if (Start->getOperand(0).getReg() == ARM::LR)
return Start; return Start;
@ -983,8 +989,8 @@ void LowOverheadLoop::Validate(ARMBasicBlockUtils *BBUtils) {
return RDA.isSafeToDefRegAt(Start, ARM::LR) ? Start : nullptr; return RDA.isSafeToDefRegAt(Start, ARM::LR) ? Start : nullptr;
}; };
InsertPt = FindStartInsertionPoint(); InsertPt = FindStartInsertionPoint(Start, RDA);
Revert = !ValidateRanges() || !InsertPt; Revert = !ValidateRanges(Start, End, BBUtils, ML) || !InsertPt;
CannotTailPredicate = !ValidateTailPredicate(InsertPt); CannotTailPredicate = !ValidateTailPredicate(InsertPt);
LLVM_DEBUG(if (!InsertPt) LLVM_DEBUG(if (!InsertPt)