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IndVarSimplify: Don't let LFTR compare against a poison value
LinearFunctionTestReplace tries to use the *next* indvar to compare against when possible. However, it may be the case that the calculation for the next indvar has NUW/NSW flags and that it may only be safely used inside the loop. Using it in a comparison to calculate the exit condition could result in observing poison. This fixes PR20680. Differential Revision: http://reviews.llvm.org/D5174 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217102 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
parent
699fd1909e
commit
c0f2b8b528
@ -1641,15 +1641,27 @@ LinearFunctionTestReplace(Loop *L,
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// compare against the post-incremented value, otherwise we must compare
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// against the preincremented value.
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if (L->getExitingBlock() == L->getLoopLatch()) {
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// Add one to the "backedge-taken" count to get the trip count.
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// This addition may overflow, which is valid as long as the comparison is
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// truncated to BackedgeTakenCount->getType().
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IVCount = SE->getAddExpr(BackedgeTakenCount,
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SE->getConstant(BackedgeTakenCount->getType(), 1));
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// The BackedgeTaken expression contains the number of times that the
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// backedge branches to the loop header. This is one less than the
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// number of times the loop executes, so use the incremented indvar.
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CmpIndVar = IndVar->getIncomingValueForBlock(L->getExitingBlock());
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llvm::Value *IncrementedIndvar = IndVar->getIncomingValueForBlock(L->getExitingBlock());
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const auto *IncrementedIndvarSCEV =
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cast<SCEVAddRecExpr>(SE->getSCEV(IncrementedIndvar));
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// It is unsafe to use the incremented indvar if it has a wrapping flag, we
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// don't want to compare against a poison value. Check the SCEV that
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// corresponds to the incremented indvar, the SCEVExpander will only insert
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// flags in the IR if the SCEV originally had wrapping flags.
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if (ScalarEvolution::maskFlags(IncrementedIndvarSCEV->getNoWrapFlags(),
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SCEV::FlagNUW | SCEV::FlagNSW) ==
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SCEV::FlagAnyWrap) {
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// Add one to the "backedge-taken" count to get the trip count.
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// This addition may overflow, which is valid as long as the comparison is
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// truncated to BackedgeTakenCount->getType().
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IVCount =
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SE->getAddExpr(BackedgeTakenCount,
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SE->getConstant(BackedgeTakenCount->getType(), 1));
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CmpIndVar = IncrementedIndvar;
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}
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}
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Value *ExitCnt = genLoopLimit(IndVar, IVCount, L, Rewriter, SE);
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@ -6,7 +6,7 @@ target triple = "thumbv7-apple-darwin"
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; CHECK-LABEL: @test(
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; CHECK: if.end.i126:
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; CHECK: %exitcond = icmp ne i8* %incdec.ptr.i, getelementptr (i8* null, i32 undef)
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; CHECK: %exitcond = icmp ne i8* %destYPixelPtr.010.i, getelementptr (i8* null, i32 undef)
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define void @test() nounwind {
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entry:
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br label %while.cond
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@ -11,7 +11,7 @@ entry:
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br i1 %cmp1, label %for.body, label %for.end
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; Make sure the added GEP has the right index type
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; CHECK: %lftr.limit = getelementptr i8 addrspace(2)* %base, i8 %0
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; CHECK: %lftr.limit = getelementptr i8 addrspace(2)* %base, i8
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; CHECK: for.body:
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; CHECK: phi i8 addrspace(2)*
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@ -43,7 +43,7 @@ entry:
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br i1 %cmp1, label %for.body, label %for.end
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; Make sure the added GEP has the right index type
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; CHECK: %lftr.limit = getelementptr i8 addrspace(3)* %base, i16 %0
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; CHECK: %lftr.limit = getelementptr i8 addrspace(3)* %base, i16
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; CHECK: for.body:
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; CHECK: phi i8 addrspace(3)*
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@ -2,7 +2,7 @@
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; CHECK-LABEL: @foo(
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; CHECK-NOT: %lftr.wideiv = trunc i32 %indvars.iv.next to i16
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; CHECK: %exitcond = icmp ne i32 %indvars.iv.next, 512
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; CHECK: %exitcond = icmp ne i32 %indvars.iv, 511
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define void @foo() #0 {
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entry:
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br label %for.body
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@ -21,7 +21,7 @@ for.end: ; preds = %for.body
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; Check that post-incrementing the backedge taken count does not overflow.
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; CHECK-LABEL: @postinc(
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; CHECK: icmp eq i32 %indvars.iv.next, 256
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; CHECK: icmp eq i32 %indvars.iv, 255
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define i32 @postinc() #0 {
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entry:
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br label %do.body
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@ -82,15 +82,23 @@ exit:
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; Perform LFTR without generating extra preheader code.
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define void @guardedloop([0 x double]* %matrix, [0 x double]* %vector,
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i32 %irow, i32 %ilead) nounwind {
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; CHECK: entry:
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; CHECK-NOT: zext
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; CHECK-NOT: add
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; CHECK: loop:
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; CHECK: phi i64
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; CHECK: phi i64
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; CHECK-LABEL: @guardedloop(
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; CHECK-LABEL: entry:
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; CHECK-NEXT: %[[cmp:.*]] = icmp slt i32 1, %irow
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; CHECK-NEXT: br i1 %[[cmp]], label %[[loop_preheader:.*]], label %[[return:.*]]
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; CHECK: [[loop_preheader]]:
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; CHECK-NEXT: %[[sext:.*]] = sext i32 %ilead to i64
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; CHECK-NEXT: %[[add:.*]] = add i32 %irow, -1
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; CHECK-NEXT: br label %[[loop:.*]]
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; CHECK: [[loop]]:
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; CHECK-NEXT: %[[indvars_iv2:.*]] = phi i64
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; CHECK-NEXT: phi i64
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; CHECK-NOT: phi
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; CHECK: icmp ne
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; CHECK: br i1
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; CHECK: %[[lftr_wideiv:.*]] = trunc i64 %[[indvars_iv2]] to i32
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; CHECK-NEXT: %[[exitcond:.*]] = icmp ne i32 %[[lftr_wideiv]], %[[add]]
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; CHECK-NEXT: br i1 %[[exitcond]], label %[[loop]], label
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entry:
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%cmp = icmp slt i32 1, %irow
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br i1 %cmp, label %loop, label %return
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219
test/Transforms/IndVarSimplify/pr20680.ll
Normal file
219
test/Transforms/IndVarSimplify/pr20680.ll
Normal file
@ -0,0 +1,219 @@
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; RUN: opt < %s -indvars -S | FileCheck %s
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@a = common global i32 0, align 4
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@c = common global i32 0, align 4
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@b = common global i32 0, align 4
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define void @f() {
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; CHECK-LABEL: @f(
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; CHECK-LABEL: entry:
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; CHECK: br label %[[for_cond2_preheader:.*]]
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; CHECK: [[for_cond2_preheader]]:
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; CHECK-NEXT: %[[indvars_iv:.*]] = phi i32 [ %[[indvars_iv_next:.*]], %[[for_inc13:.*]] ], [ -14, %entry ]
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; br i1 {{.*}}, label %[[for_inc13]], label %
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entry:
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%0 = load i32* @a, align 4
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%tobool2 = icmp eq i32 %0, 0
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%1 = load i32* @a, align 4
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%tobool = icmp eq i32 %1, 0
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br label %for.cond2.preheader
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for.cond2.preheader: ; preds = %for.inc13, %entry
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%storemerge15 = phi i8 [ -14, %entry ], [ %inc14, %for.inc13 ]
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br i1 %tobool2, label %for.inc13, label %for.body3.lr.ph
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for.body3.lr.ph: ; preds = %for.cond2.preheader
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%tobool5 = icmp eq i8 %storemerge15, 0
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%conv7 = sext i8 %storemerge15 to i32
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%2 = add nsw i32 %conv7, 1
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%3 = icmp ult i32 %2, 3
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%div = select i1 %3, i32 %conv7, i32 0
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br i1 %tobool5, label %for.body3.lr.ph.split.us, label %for.body3.lr.ph.for.body3.lr.ph.split_crit_edge
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for.body3.lr.ph.for.body3.lr.ph.split_crit_edge: ; preds = %for.body3.lr.ph
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br label %for.body3.lr.ph.split
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for.body3.lr.ph.split.us: ; preds = %for.body3.lr.ph
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br i1 %tobool, label %for.body3.lr.ph.split.us.split.us, label %for.body3.lr.ph.split.us.for.body3.lr.ph.split.us.split_crit_edge
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for.body3.lr.ph.split.us.for.body3.lr.ph.split.us.split_crit_edge: ; preds = %for.body3.lr.ph.split.us
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br label %for.body3.lr.ph.split.us.split
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for.body3.lr.ph.split.us.split.us: ; preds = %for.body3.lr.ph.split.us
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br label %for.body3.us.us
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for.body3.us.us: ; preds = %for.cond2.loopexit.us.us, %for.body3.lr.ph.split.us.split.us
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br i1 true, label %cond.false.us.us, label %cond.end.us.us
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cond.false.us.us: ; preds = %for.body3.us.us
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br label %cond.end.us.us
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cond.end.us.us: ; preds = %cond.false.us.us, %for.body3.us.us
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%cond.us.us = phi i32 [ %div, %cond.false.us.us ], [ %conv7, %for.body3.us.us ]
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%4 = load i32* @b, align 4
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%cmp91.us.us = icmp slt i32 %4, 1
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br i1 %cmp91.us.us, label %for.inc.lr.ph.us.us, label %for.cond2.loopexit.us.us
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for.cond2.loopexit.us.us: ; preds = %for.cond8.for.cond2.loopexit_crit_edge.us.us, %cond.end.us.us
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br i1 true, label %for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa.us, label %for.body3.us.us
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for.inc.lr.ph.us.us: ; preds = %cond.end.us.us
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br label %for.inc.us.us
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for.cond8.for.cond2.loopexit_crit_edge.us.us: ; preds = %for.inc.us.us
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%inc.lcssa.us.us = phi i32 [ %inc.us.us, %for.inc.us.us ]
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store i32 %inc.lcssa.us.us, i32* @b, align 4
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br label %for.cond2.loopexit.us.us
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for.inc.us.us: ; preds = %for.inc.us.us, %for.inc.lr.ph.us.us
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%5 = phi i32 [ %4, %for.inc.lr.ph.us.us ], [ %inc.us.us, %for.inc.us.us ]
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%inc.us.us = add nsw i32 %5, 1
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%cmp9.us.us = icmp slt i32 %inc.us.us, 1
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br i1 %cmp9.us.us, label %for.inc.us.us, label %for.cond8.for.cond2.loopexit_crit_edge.us.us
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for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa.us: ; preds = %for.cond2.loopexit.us.us
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%cond.lcssa.ph.us.ph.us = phi i32 [ %cond.us.us, %for.cond2.loopexit.us.us ]
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br label %for.cond2.for.inc13_crit_edge.us-lcssa.us
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for.body3.lr.ph.split.us.split: ; preds = %for.body3.lr.ph.split.us.for.body3.lr.ph.split.us.split_crit_edge
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br label %for.body3.us
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for.body3.us: ; preds = %for.cond2.loopexit.us, %for.body3.lr.ph.split.us.split
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br i1 true, label %cond.false.us, label %cond.end.us
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cond.false.us: ; preds = %for.body3.us
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br label %cond.end.us
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cond.end.us: ; preds = %cond.false.us, %for.body3.us
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%cond.us = phi i32 [ %div, %cond.false.us ], [ %conv7, %for.body3.us ]
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%6 = load i32* @b, align 4
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%cmp91.us = icmp slt i32 %6, 1
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br i1 %cmp91.us, label %for.inc.lr.ph.us, label %for.cond2.loopexit.us
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for.inc.us: ; preds = %for.inc.lr.ph.us, %for.inc.us
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%7 = phi i32 [ %6, %for.inc.lr.ph.us ], [ %inc.us, %for.inc.us ]
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%inc.us = add nsw i32 %7, 1
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%cmp9.us = icmp slt i32 %inc.us, 1
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br i1 %cmp9.us, label %for.inc.us, label %for.cond8.for.cond2.loopexit_crit_edge.us
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for.cond2.loopexit.us: ; preds = %for.cond8.for.cond2.loopexit_crit_edge.us, %cond.end.us
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br i1 false, label %for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa, label %for.body3.us
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for.inc.lr.ph.us: ; preds = %cond.end.us
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br label %for.inc.us
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for.cond8.for.cond2.loopexit_crit_edge.us: ; preds = %for.inc.us
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%inc.lcssa.us = phi i32 [ %inc.us, %for.inc.us ]
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store i32 %inc.lcssa.us, i32* @b, align 4
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br label %for.cond2.loopexit.us
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for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa: ; preds = %for.cond2.loopexit.us
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%cond.lcssa.ph.us.ph = phi i32 [ %cond.us, %for.cond2.loopexit.us ]
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br label %for.cond2.for.inc13_crit_edge.us-lcssa.us
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for.cond2.for.inc13_crit_edge.us-lcssa.us: ; preds = %for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa, %for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa.us
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%cond.lcssa.ph.us = phi i32 [ %cond.lcssa.ph.us.ph, %for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa ], [ %cond.lcssa.ph.us.ph.us, %for.cond2.for.inc13_crit_edge.us-lcssa.us.us-lcssa.us ]
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br label %for.cond2.for.inc13_crit_edge
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for.body3.lr.ph.split: ; preds = %for.body3.lr.ph.for.body3.lr.ph.split_crit_edge
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br i1 %tobool, label %for.body3.lr.ph.split.split.us, label %for.body3.lr.ph.split.for.body3.lr.ph.split.split_crit_edge
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for.body3.lr.ph.split.for.body3.lr.ph.split.split_crit_edge: ; preds = %for.body3.lr.ph.split
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br label %for.body3.lr.ph.split.split
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for.body3.lr.ph.split.split.us: ; preds = %for.body3.lr.ph.split
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br label %for.body3.us3
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for.body3.us3: ; preds = %for.cond2.loopexit.us11, %for.body3.lr.ph.split.split.us
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br i1 false, label %cond.false.us4, label %cond.end.us5
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cond.false.us4: ; preds = %for.body3.us3
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br label %cond.end.us5
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cond.end.us5: ; preds = %cond.false.us4, %for.body3.us3
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%cond.us6 = phi i32 [ %div, %cond.false.us4 ], [ %conv7, %for.body3.us3 ]
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%8 = load i32* @b, align 4
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%cmp91.us7 = icmp slt i32 %8, 1
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br i1 %cmp91.us7, label %for.inc.lr.ph.us12, label %for.cond2.loopexit.us11
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for.inc.us8: ; preds = %for.inc.lr.ph.us12, %for.inc.us8
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%9 = phi i32 [ %8, %for.inc.lr.ph.us12 ], [ %inc.us9, %for.inc.us8 ]
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%inc.us9 = add nsw i32 %9, 1
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%cmp9.us10 = icmp slt i32 %inc.us9, 1
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br i1 %cmp9.us10, label %for.inc.us8, label %for.cond8.for.cond2.loopexit_crit_edge.us13
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for.cond2.loopexit.us11: ; preds = %for.cond8.for.cond2.loopexit_crit_edge.us13, %cond.end.us5
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br i1 true, label %for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa.us, label %for.body3.us3
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for.inc.lr.ph.us12: ; preds = %cond.end.us5
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br label %for.inc.us8
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for.cond8.for.cond2.loopexit_crit_edge.us13: ; preds = %for.inc.us8
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%inc.lcssa.us14 = phi i32 [ %inc.us9, %for.inc.us8 ]
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store i32 %inc.lcssa.us14, i32* @b, align 4
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br label %for.cond2.loopexit.us11
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for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa.us: ; preds = %for.cond2.loopexit.us11
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%cond.lcssa.ph.ph.us = phi i32 [ %cond.us6, %for.cond2.loopexit.us11 ]
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br label %for.cond2.for.inc13_crit_edge.us-lcssa
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for.body3.lr.ph.split.split: ; preds = %for.body3.lr.ph.split.for.body3.lr.ph.split.split_crit_edge
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br label %for.body3
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for.cond8.for.cond2.loopexit_crit_edge: ; preds = %for.inc
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%inc.lcssa = phi i32 [ %inc, %for.inc ]
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store i32 %inc.lcssa, i32* @b, align 4
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br label %for.cond2.loopexit
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for.cond2.loopexit: ; preds = %cond.end, %for.cond8.for.cond2.loopexit_crit_edge
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br i1 false, label %for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa, label %for.body3
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for.body3: ; preds = %for.cond2.loopexit, %for.body3.lr.ph.split.split
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br i1 false, label %cond.false, label %cond.end
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cond.false: ; preds = %for.body3
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br label %cond.end
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cond.end: ; preds = %cond.false, %for.body3
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%cond = phi i32 [ %div, %cond.false ], [ %conv7, %for.body3 ]
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%10 = load i32* @b, align 4
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%cmp91 = icmp slt i32 %10, 1
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br i1 %cmp91, label %for.inc.lr.ph, label %for.cond2.loopexit
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for.inc.lr.ph: ; preds = %cond.end
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br label %for.inc
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for.inc: ; preds = %for.inc, %for.inc.lr.ph
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%11 = phi i32 [ %10, %for.inc.lr.ph ], [ %inc, %for.inc ]
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%inc = add nsw i32 %11, 1
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%cmp9 = icmp slt i32 %inc, 1
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br i1 %cmp9, label %for.inc, label %for.cond8.for.cond2.loopexit_crit_edge
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for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa: ; preds = %for.cond2.loopexit
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%cond.lcssa.ph.ph = phi i32 [ %cond, %for.cond2.loopexit ]
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br label %for.cond2.for.inc13_crit_edge.us-lcssa
|
||||
|
||||
for.cond2.for.inc13_crit_edge.us-lcssa: ; preds = %for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa, %for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa.us
|
||||
%cond.lcssa.ph = phi i32 [ %cond.lcssa.ph.ph, %for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa ], [ %cond.lcssa.ph.ph.us, %for.cond2.for.inc13_crit_edge.us-lcssa.us-lcssa.us ]
|
||||
br label %for.cond2.for.inc13_crit_edge
|
||||
|
||||
for.cond2.for.inc13_crit_edge: ; preds = %for.cond2.for.inc13_crit_edge.us-lcssa, %for.cond2.for.inc13_crit_edge.us-lcssa.us
|
||||
%cond.lcssa = phi i32 [ %cond.lcssa.ph, %for.cond2.for.inc13_crit_edge.us-lcssa ], [ %cond.lcssa.ph.us, %for.cond2.for.inc13_crit_edge.us-lcssa.us ]
|
||||
store i32 %cond.lcssa, i32* @c, align 4
|
||||
br label %for.inc13
|
||||
|
||||
; CHECK: [[for_inc13]]:
|
||||
; CHECK-NEXT: %[[indvars_iv_next]] = add nuw nsw i32 %[[indvars_iv]], 1
|
||||
; CHECK-NEXT: %[[exitcond4:.*]] = icmp ne i32 %[[indvars_iv]], -1
|
||||
; CHECK-NEXT: br i1 %[[exitcond4]], label %[[for_cond2_preheader]], label %[[for_end15:.*]]
|
||||
for.inc13: ; preds = %for.cond2.for.inc13_crit_edge, %for.cond2.preheader
|
||||
%inc14 = add i8 %storemerge15, 1
|
||||
%cmp = icmp ugt i8 %inc14, 50
|
||||
br i1 %cmp, label %for.cond2.preheader, label %for.end15
|
||||
|
||||
; CHECK: [[for_end15]]:
|
||||
; CHECK-NEXT: ret void
|
||||
for.end15: ; preds = %for.inc13
|
||||
ret void
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user