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[CodeGenPrepare][AddressingModeMatcher] Give up on type promotion if the

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transformation does not bring any immediate benefits and introduce an illegal
operation. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201439 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2014-02-14 22:23:22 +00:00
parent 5f80594797
commit 038600b42e
2 changed files with 33 additions and 5 deletions
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36
lib/Transforms/Scalar/CodeGenPrepare.cpp
View File

@ -1376,6 +1376,8 @@ private:
ExtAddrMode &AMBefore,
ExtAddrMode &AMAfter);
bool ValueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);
bool IsPromotionProfitable(unsigned MatchedSize, unsigned SizeWithPromotion,
Value *PromotedOperand) const;
};
/// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
@ -1728,6 +1730,35 @@ TypePromotionHelper::promoteOperandForOther(Instruction *SExt,
return SExtOpnd;
}
/// IsPromotionProfitable - Check whether or not promoting an instruction
/// to a wider type was profitable.
/// \p MatchedSize gives the number of instructions that have been matched
/// in the addressing mode after the promotion was applied.
/// \p SizeWithPromotion gives the number of created instructions for
/// the promotion plus the number of instructions that have been
/// matched in the addressing mode before the promotion.
/// \p PromotedOperand is the value that has been promoted.
/// \return True if the promotion is profitable, false otherwise.
bool
AddressingModeMatcher::IsPromotionProfitable(unsigned MatchedSize,
unsigned SizeWithPromotion,
Value *PromotedOperand) const {
// We folded less instructions than what we created to promote the operand.
// This is not profitable.
if (MatchedSize < SizeWithPromotion)
return false;
if (MatchedSize > SizeWithPromotion)
return true;
// The promotion is neutral but it may help folding the sign extension in
// loads for instance.
// Check that we did not create an illegal instruction.
Instruction *PromotedInst = dyn_cast<Instruction>(PromotedOperand);
if (!PromotedInst)
return false;
return TLI.isOperationLegalOrCustom(PromotedInst->getOpcode(),
EVT::getEVT(PromotedInst->getType()));
}
/// MatchOperationAddr - Given an instruction or constant expr, see if we can
/// fold the operation into the addressing mode. If so, update the addressing
/// mode and return true, otherwise return false without modifying AddrMode.
@ -1935,9 +1966,8 @@ bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
unsigned OldSize = AddrModeInsts.size();
if (!MatchAddr(PromotedOperand, Depth) ||
// We fold less instructions than what we created.
// Undo at this point.
(OldSize + CreatedInsts > AddrModeInsts.size())) {
!IsPromotionProfitable(AddrModeInsts.size(), OldSize + CreatedInsts,
PromotedOperand)) {
AddrMode = BackupAddrMode;
AddrModeInsts.resize(OldSize);
DEBUG(dbgs() << "Sign extension does not pay off: rollback\n");

2
test/CodeGen/R600/codegen-prepare-addrmode-sext.ll
View File

@ -3,8 +3,6 @@
target datalayout = "e-p:32:32-p1:64:64-p2:64:64-p3:32:32-p4:32:32-p5:64:64-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64"
target triple = "r600--"
; XFAIL: *
; CHECK-LABEL: @test
; CHECK: mul
; CHECK-NEXT: sext