[llvm] r293202 - [IfConversion] Use reverse_iterator to simplify. NFC
Kyle Butt via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 26 12:02:47 PST 2017
Author: iteratee
Date: Thu Jan 26 14:02:47 2017
New Revision: 293202
URL: http://llvm.org/viewvc/llvm-project?rev=293202&view=rev
Log:
[IfConversion] Use reverse_iterator to simplify. NFC
This simplifies skipping debug instructions and shrinking ranges.
Modified:
llvm/trunk/lib/CodeGen/IfConversion.cpp
Modified: llvm/trunk/lib/CodeGen/IfConversion.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/IfConversion.cpp?rev=293202&r1=293201&r2=293202&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/IfConversion.cpp (original)
+++ llvm/trunk/lib/CodeGen/IfConversion.cpp Thu Jan 26 14:02:47 2017
@@ -588,19 +588,6 @@ bool IfConverter::ValidTriangle(BBInfo &
return TExit && TExit == FalseBBI.BB;
}
-/// Shrink the provided inclusive range by one instruction.
-/// If the range was one instruction (\p It == \p Begin), It is not modified,
-/// but \p Empty is set to true.
-static inline void shrinkInclusiveRange(
- MachineBasicBlock::iterator &Begin,
- MachineBasicBlock::iterator &It,
- bool &Empty) {
- if (It == Begin)
- Empty = true;
- else
- It--;
-}
-
/// Count duplicated instructions and move the iterators to show where they
/// are.
/// @param TIB True Iterator Begin
@@ -633,10 +620,8 @@ bool IfConverter::CountDuplicatedInstruc
while (TIB != TIE && FIB != FIE) {
// Skip dbg_value instructions. These do not count.
TIB = skipDebugInstructionsForward(TIB, TIE);
- if(TIB == TIE)
- break;
FIB = skipDebugInstructionsForward(FIB, FIE);
- if(FIB == FIE)
+ if (TIB == TIE || FIB == FIE)
break;
if (!TIB->isIdenticalTo(*FIB))
break;
@@ -656,58 +641,42 @@ bool IfConverter::CountDuplicatedInstruc
if (TIB == TIE || FIB == FIE)
return true;
// Now, in preparation for counting duplicate instructions at the ends of the
- // blocks, move the end iterators up past any branch instructions.
- --TIE;
- --FIE;
-
- // After this point TIB and TIE define an inclusive range, which means that
- // TIB == TIE is true when there is one more instruction to consider, not at
- // the end. Because we may not be able to go before TIB, we need a flag to
- // indicate a completely empty range.
- bool TEmpty = false, FEmpty = false;
-
- // Upon exit TIE and FIE will both point at the last non-shared instruction.
- // They need to be moved forward to point past the last non-shared
- // instruction if the range they delimit is non-empty.
- auto IncrementEndIteratorsOnExit = make_scope_exit([&]() {
- if (!TEmpty)
- ++TIE;
- if (!FEmpty)
- ++FIE;
- });
+ // blocks, switch to reverse_iterators. Note that getReverse() returns an
+ // iterator that points to the same instruction, unlike std::reverse_iterator.
+ // We have to do our own shifting so that we get the same range.
+ MachineBasicBlock::reverse_iterator RTIE = std::next(TIE.getReverse());
+ MachineBasicBlock::reverse_iterator RFIE = std::next(FIE.getReverse());
+ const MachineBasicBlock::reverse_iterator RTIB = std::next(TIB.getReverse());
+ const MachineBasicBlock::reverse_iterator RFIB = std::next(FIB.getReverse());
if (!TBB.succ_empty() || !FBB.succ_empty()) {
if (SkipUnconditionalBranches) {
- while (!TEmpty && TIE->isUnconditionalBranch())
- shrinkInclusiveRange(TIB, TIE, TEmpty);
- while (!FEmpty && FIE->isUnconditionalBranch())
- shrinkInclusiveRange(FIB, FIE, FEmpty);
+ while (RTIE != RTIB && RTIE->isUnconditionalBranch())
+ ++RTIE;
+ while (RFIE != RFIB && RFIE->isUnconditionalBranch())
+ ++RFIE;
}
}
- // If Dups1 includes all of a block, then don't count duplicate
- // instructions at the end of the blocks.
- if (TEmpty || FEmpty)
- return true;
-
// Count duplicate instructions at the ends of the blocks.
- while (!TEmpty && !FEmpty) {
+ while (RTIE != RTIB && RFIE != RFIB) {
// Skip dbg_value instructions. These do not count.
- TIE = skipDebugInstructionsBackward(TIE, TIB);
- FIE = skipDebugInstructionsBackward(FIE, FIB);
- TEmpty = TIE == TIB && TIE->isDebugValue();
- FEmpty = FIE == FIB && FIE->isDebugValue();
- if (TEmpty || FEmpty)
+ // Note that these are reverse iterators going forward.
+ RTIE = skipDebugInstructionsForward(RTIE, RTIB);
+ RFIE = skipDebugInstructionsForward(RFIE, RFIB);
+ if (RTIE == RTIB || RFIE == RFIB)
break;
- if (!TIE->isIdenticalTo(*FIE))
+ if (!RTIE->isIdenticalTo(*RFIE))
break;
// We have to verify that any branch instructions are the same, and then we
// don't count them toward the # of duplicate instructions.
- if (!TIE->isBranch())
+ if (!RTIE->isBranch())
++Dups2;
- shrinkInclusiveRange(TIB, TIE, TEmpty);
- shrinkInclusiveRange(FIB, FIE, FEmpty);
+ ++RTIE;
+ ++RFIE;
}
+ TIE = std::next(RTIE.getReverse());
+ FIE = std::next(RFIE.getReverse());
return true;
}
@@ -741,25 +710,21 @@ bool IfConverter::RescanInstructions(
static void verifySameBranchInstructions(
MachineBasicBlock *MBB1,
MachineBasicBlock *MBB2) {
- MachineBasicBlock::iterator B1 = MBB1->begin();
- MachineBasicBlock::iterator B2 = MBB2->begin();
- MachineBasicBlock::iterator E1 = std::prev(MBB1->end());
- MachineBasicBlock::iterator E2 = std::prev(MBB2->end());
- bool Empty1 = false, Empty2 = false;
- while (!Empty1 && !Empty2) {
- E1 = skipDebugInstructionsBackward(E1, B1);
- E2 = skipDebugInstructionsBackward(E2, B2);
- Empty1 = E1 == B1 && E1->isDebugValue();
- Empty2 = E2 == B2 && E2->isDebugValue();
-
- if (Empty1 && Empty2)
+ const MachineBasicBlock::reverse_iterator B1 = MBB1->rend();
+ const MachineBasicBlock::reverse_iterator B2 = MBB2->rend();
+ MachineBasicBlock::reverse_iterator E1 = MBB1->rbegin();
+ MachineBasicBlock::reverse_iterator E2 = MBB2->rbegin();
+ while (E1 != B1 && E2 != B2) {
+ skipDebugInstructionsForward(E1, B1);
+ skipDebugInstructionsForward(E2, B2);
+ if (E1 == B1 && E2 == B2)
break;
- if (Empty1) {
+ if (E1 == B1) {
assert(!E2->isBranch() && "Branch mis-match, one block is empty.");
break;
}
- if (Empty2) {
+ if (E2 == B2) {
assert(!E1->isBranch() && "Branch mis-match, one block is empty.");
break;
}
@@ -769,8 +734,8 @@ static void verifySameBranchInstructions
"Branch mis-match, branch instructions don't match.");
else
break;
- shrinkInclusiveRange(B1, E1, Empty1);
- shrinkInclusiveRange(B2, E2, Empty2);
+ ++E1;
+ ++E2;
}
}
#endif
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