From 0cd23c842e6e1d0747fb14661f1bac0dbbac0cee Mon Sep 17 00:00:00 2001 From: NAKAMURA Takumi Date: Mon, 2 Mar 2015 01:14:03 +0000 Subject: [PATCH] Revert r230921, "Revert some changes that were made to fix PR20680.", for now. It caused a failure on clang/test/Misc/backend-optimization-failure.cpp . llvm-svn: 230929 --- llvm/lib/Transforms/Scalar/IndVarSimplify.cpp | 48 +++++++++++++++++++--- .../IndVarSimplify/2011-10-27-lftrnull.ll | 2 +- .../IndVarSimplify/lftr-address-space-pointers.ll | 4 +- llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll | 24 +++++++---- 4 files changed, 61 insertions(+), 17 deletions(-) diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp index 462c2b6..f99ebbc 100644 --- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -1705,15 +1705,51 @@ LinearFunctionTestReplace(Loop *L, // compare against the post-incremented value, otherwise we must compare // against the preincremented value. if (L->getExitingBlock() == L->getLoopLatch()) { - // Add one to the "backedge-taken" count to get the trip count. - // This addition may overflow, which is valid as long as the comparison is - // truncated to BackedgeTakenCount->getType(). - IVCount = SE->getAddExpr(BackedgeTakenCount, - SE->getConstant(BackedgeTakenCount->getType(), 1)); // The BackedgeTaken expression contains the number of times that the // backedge branches to the loop header. This is one less than the // number of times the loop executes, so use the incremented indvar. - CmpIndVar = IndVar->getIncomingValueForBlock(L->getExitingBlock()); + llvm::Value *IncrementedIndvar = + IndVar->getIncomingValueForBlock(L->getExitingBlock()); + const auto *IncrementedIndvarSCEV = + cast(SE->getSCEV(IncrementedIndvar)); + // It is unsafe to use the incremented indvar if it has a wrapping flag, we + // don't want to compare against a poison value. Check the SCEV that + // corresponds to the incremented indvar, the SCEVExpander will only insert + // flags in the IR if the SCEV originally had wrapping flags. + // FIXME: In theory, SCEV could drop flags even though they exist in IR. + // A more robust solution would involve getting a new expression for + // CmpIndVar by applying non-NSW/NUW AddExprs. + auto WrappingFlags = + ScalarEvolution::setFlags(SCEV::FlagNUW, SCEV::FlagNSW); + const SCEV *IVInit = IncrementedIndvarSCEV->getStart(); + if (SE->getTypeSizeInBits(IVInit->getType()) > + SE->getTypeSizeInBits(IVCount->getType())) + IVInit = SE->getTruncateExpr(IVInit, IVCount->getType()); + unsigned BitWidth = SE->getTypeSizeInBits(IVCount->getType()); + Type *WideTy = IntegerType::get(SE->getContext(), BitWidth + 1); + // Check if InitIV + BECount+1 requires sign/zero extension. + // If not, clear the corresponding flag from WrappingFlags because it is not + // necessary for those flags in the IncrementedIndvarSCEV expression. + if (SE->getSignExtendExpr(SE->getAddExpr(IVInit, BackedgeTakenCount), + WideTy) == + SE->getAddExpr(SE->getSignExtendExpr(IVInit, WideTy), + SE->getSignExtendExpr(BackedgeTakenCount, WideTy))) + WrappingFlags = ScalarEvolution::clearFlags(WrappingFlags, SCEV::FlagNSW); + if (SE->getZeroExtendExpr(SE->getAddExpr(IVInit, BackedgeTakenCount), + WideTy) == + SE->getAddExpr(SE->getZeroExtendExpr(IVInit, WideTy), + SE->getZeroExtendExpr(BackedgeTakenCount, WideTy))) + WrappingFlags = ScalarEvolution::clearFlags(WrappingFlags, SCEV::FlagNUW); + if (!ScalarEvolution::maskFlags(IncrementedIndvarSCEV->getNoWrapFlags(), + WrappingFlags)) { + // Add one to the "backedge-taken" count to get the trip count. + // This addition may overflow, which is valid as long as the comparison is + // truncated to BackedgeTakenCount->getType(). + IVCount = + SE->getAddExpr(BackedgeTakenCount, + SE->getConstant(BackedgeTakenCount->getType(), 1)); + CmpIndVar = IncrementedIndvar; + } } Value *ExitCnt = genLoopLimit(IndVar, IVCount, L, Rewriter, SE); diff --git a/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll b/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll index f1d1139..75eaf91 100644 --- a/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll +++ b/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll @@ -6,7 +6,7 @@ target triple = "thumbv7-apple-darwin" ; CHECK-LABEL: @test( ; CHECK: if.end.i126: -; CHECK: %exitcond = icmp ne i8* %incdec.ptr.i, getelementptr (i8* null, i32 undef) +; CHECK: %exitcond = icmp ne i8* %destYPixelPtr.010.i, getelementptr (i8* null, i32 undef) define void @test() nounwind { entry: br label %while.cond diff --git a/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll b/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll index feb4b35..b23e08d 100644 --- a/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll +++ b/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll @@ -11,7 +11,7 @@ entry: br i1 %cmp1, label %for.body, label %for.end ; Make sure the added GEP has the right index type -; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(2)* %base, i8 %0 +; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(2)* %base, i8 ; CHECK: for.body: ; CHECK: phi i8 addrspace(2)* @@ -43,7 +43,7 @@ entry: br i1 %cmp1, label %for.body, label %for.end ; Make sure the added GEP has the right index type -; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(3)* %base, i16 %0 +; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(3)* %base, i16 ; CHECK: for.body: ; CHECK: phi i8 addrspace(3)* diff --git a/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll b/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll index b4e1fde..befbb9e 100644 --- a/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll +++ b/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll @@ -82,15 +82,23 @@ exit: ; Perform LFTR without generating extra preheader code. define void @guardedloop([0 x double]* %matrix, [0 x double]* %vector, i32 %irow, i32 %ilead) nounwind { -; CHECK: entry: -; CHECK-NOT: zext -; CHECK-NOT: add -; CHECK: loop: -; CHECK: phi i64 -; CHECK: phi i64 +; CHECK-LABEL: @guardedloop( +; CHECK-LABEL: entry: +; CHECK-NEXT: %[[cmp:.*]] = icmp slt i32 1, %irow +; CHECK-NEXT: br i1 %[[cmp]], label %[[loop_preheader:.*]], label %[[return:.*]] + +; CHECK: [[loop_preheader]]: +; CHECK-NEXT: %[[sext:.*]] = sext i32 %ilead to i64 +; CHECK-NEXT: %[[add:.*]] = add i32 %irow, -1 +; CHECK-NEXT: br label %[[loop:.*]] + +; CHECK: [[loop]]: +; CHECK-NEXT: %[[indvars_iv2:.*]] = phi i64 +; CHECK-NEXT: phi i64 ; CHECK-NOT: phi -; CHECK: icmp ne -; CHECK: br i1 +; CHECK: %[[lftr_wideiv:.*]] = trunc i64 %[[indvars_iv2]] to i32 +; CHECK-NEXT: %[[exitcond:.*]] = icmp ne i32 %[[lftr_wideiv]], %[[add]] +; CHECK-NEXT: br i1 %[[exitcond]], label %[[loop]], label entry: %cmp = icmp slt i32 1, %irow br i1 %cmp, label %loop, label %return -- 2.7.4