From dfe482bddddf3a03cdb1f5130e0af9e502b19d85 Mon Sep 17 00:00:00 2001 From: Tom Stellard Date: Tue, 8 Apr 2014 21:18:17 +0000 Subject: Merging r203719: ------------------------------------------------------------------------ r203719 | mzolotukhin | 2014-03-12 17:31:05 -0400 (Wed, 12 Mar 2014) | 4 lines PR17473: Don't normalize an expression during postinc transformation unless it's invertible. ------------------------------------------------------------------------ git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@205797 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/IVUsers.cpp | 23 ++++++++- test/Transforms/LoopStrengthReduce/pr17473.ll | 67 +++++++++++++++++++++++++++ 2 files changed, 88 insertions(+), 2 deletions(-) create mode 100644 test/Transforms/LoopStrengthReduce/pr17473.ll diff --git a/lib/Analysis/IVUsers.cpp b/lib/Analysis/IVUsers.cpp index b33e2cb999..5a06cdce30 100644 --- a/lib/Analysis/IVUsers.cpp +++ b/lib/Analysis/IVUsers.cpp @@ -187,15 +187,34 @@ bool IVUsers::AddUsersImpl(Instruction *I, if (AddUserToIVUsers) { // Okay, we found a user that we cannot reduce. - IVUses.push_back(new IVStrideUse(this, User, I)); - IVStrideUse &NewUse = IVUses.back(); + IVStrideUse &NewUse = AddUser(User, I); // Autodetect the post-inc loop set, populating NewUse.PostIncLoops. // The regular return value here is discarded; instead of recording // it, we just recompute it when we need it. + const SCEV *OriginalISE = ISE; ISE = TransformForPostIncUse(NormalizeAutodetect, ISE, User, I, NewUse.PostIncLoops, *SE, *DT); + + // PostIncNormalization effectively simplifies the expression under + // pre-increment assumptions. Those assumptions (no wrapping) might not + // hold for the post-inc value. Catch such cases by making sure the + // transformation is invertible. + if (OriginalISE != ISE) { + const SCEV *DenormalizedISE = + TransformForPostIncUse(Denormalize, ISE, User, I, + NewUse.PostIncLoops, *SE, *DT); + + // If we normalized the expression, but denormalization doesn't give the + // original one, discard this user. + if (OriginalISE != DenormalizedISE) { + DEBUG(dbgs() << " DISCARDING (NORMALIZATION ISN'T INVERTIBLE): " + << *ISE << '\n'); + IVUses.pop_back(); + return false; + } + } DEBUG(if (SE->getSCEV(I) != ISE) dbgs() << " NORMALIZED TO: " << *ISE << '\n'); } diff --git a/test/Transforms/LoopStrengthReduce/pr17473.ll b/test/Transforms/LoopStrengthReduce/pr17473.ll new file mode 100644 index 0000000000..4204abc7ca --- /dev/null +++ b/test/Transforms/LoopStrengthReduce/pr17473.ll @@ -0,0 +1,67 @@ +; RUN: opt < %s -loop-reduce -S | FileCheck %s + +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32-S128" +target triple = "x86_64-apple-macosx10.9.0" + +; LSR shouldn't normalize IV if it can't be denormalized to the original +; expression. In this testcase, the normalized expression was denormalized to +; an expression different from the original, and we were losing sign extension. + +; CHECK: [[TMP:%[a-z]+]] = trunc i32 {{.*}} to i8 +; CHECK: {{%[a-z0-9]+}} = sext i8 [[TMP]] to i32 + +@j = common global i32 0, align 4 +@c = common global i32 0, align 4 +@g = common global i32 0, align 4 +@h = common global i8 0, align 1 +@d = common global i32 0, align 4 +@i = common global i32 0, align 4 +@e = common global i32 0, align 4 +@.str = private unnamed_addr constant [4 x i8] c"%x\0A\00", align 1 +@a = common global i32 0, align 4 +@b = common global i16 0, align 2 + +; Function Attrs: nounwind optsize ssp uwtable +define i32 @main() #0 { +entry: + store i8 0, i8* @h, align 1 + %0 = load i32* @j, align 4 + %tobool.i = icmp eq i32 %0, 0 + %1 = load i32* @d, align 4 + %cmp3 = icmp sgt i32 %1, -1 + %.lobit = lshr i32 %1, 31 + %.lobit.not = xor i32 %.lobit, 1 + br label %for.body + +for.body: ; preds = %entry, %fn3.exit + %inc9 = phi i8 [ 0, %entry ], [ %inc, %fn3.exit ] + %conv = sext i8 %inc9 to i32 + br i1 %tobool.i, label %fn3.exit, label %land.rhs.i + +land.rhs.i: ; preds = %for.body + store i32 0, i32* @c, align 4 + br label %fn3.exit + +fn3.exit: ; preds = %for.body, %land.rhs.i + %inc = add i8 %inc9, 1 + %cmp = icmp sgt i8 %inc, -1 + br i1 %cmp, label %for.body, label %for.end + +for.end: ; preds = %fn3.exit + %.lobit.not. = select i1 %cmp3, i32 %.lobit.not, i32 0 + store i32 %conv, i32* @g, align 4 + store i32 %.lobit.not., i32* @i, align 4 + store i8 %inc, i8* @h, align 1 + %conv7 = sext i8 %inc to i32 + %add = add nsw i32 %conv7, %conv + store i32 %add, i32* @e, align 4 + %call = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @.str, i64 0, i64 0), i32 %add) #2 + ret i32 0 +} + +; Function Attrs: nounwind optsize +declare i32 @printf(i8* nocapture readonly, ...) #1 + +attributes #0 = { nounwind optsize ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } +attributes #1 = { nounwind optsize "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } +attributes #2 = { nounwind optsize } -- cgit v1.2.3