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[LoopInterchange] Skip zext instructions when looking for induction var.

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Summary:
SimplifyIndVar may introduce zext instructions to widen arguments of the
loop exit check. They should not prevent us from splitting the loop at
the induction variable, but maybe the check should be more conservative,
e.g. making sure it only extends arguments used by a comparison?

Reviewers: karthikthecool, mcrosier, mzolotukhin

Reviewed By: mcrosier

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D34879

llvm-svn: 311783
This commit is contained in:
Florian Hahn 2017-08-25 16:52:29 +00:00
parent bdcf335b6b
commit 51630ed7b4
2 changed files with 82 additions and 1 deletions
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3
lib/Transforms/Scalar/LoopInterchange.cpp
View File

@ -908,7 +908,8 @@ bool LoopInterchangeLegality::currentLimitations() {
bool FoundInduction = false;
for (const Instruction &I : reverse(*InnerLoopLatch)) {
if (isa<BranchInst>(I) || isa<CmpInst>(I) || isa<TruncInst>(I))
if (isa<BranchInst>(I) || isa<CmpInst>(I) || isa<TruncInst>(I) ||
isa<ZExtInst>(I))
continue;
// We found an instruction. If this is not induction variable then it is not

80
test/Transforms/LoopInterchange/interchange-insts-between-indvar.ll Normal file
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@ -0,0 +1,80 @@
; RUN: opt < %s -basicaa -loop-interchange -S | FileCheck %s
@A10 = local_unnamed_addr global [3 x [3 x i32]] zeroinitializer, align 16
;; Test to make sure we can handle zext intructions introduced by
;; IndVarSimplify.
;;
;; for (int i = 0; i < 2; ++i)
;; for(int j = 0; j < n; ++j) {
;; A[j][i] = i;
;; }
@A11 = local_unnamed_addr global [3 x [3 x i32]] zeroinitializer, align 16
define void @interchange_11(i32 %n) {
entry:
br label %for.cond1.preheader
for.cond.loopexit: ; preds = %for.body4
%exitcond28 = icmp ne i64 %indvars.iv.next27, 2
br i1 %exitcond28, label %for.cond1.preheader, label %for.cond.cleanup
for.cond1.preheader: ; preds = %for.cond.loopexit, %entry
%indvars.iv26 = phi i64 [ 0, %entry ], [ %indvars.iv.next27, %for.cond.loopexit ]
%indvars.iv.next27 = add nuw nsw i64 %indvars.iv26, 1
br label %for.body4
for.cond.cleanup: ; preds = %for.cond.loopexit
ret void
for.body4: ; preds = %for.body4, %for.cond1.preheader
%indvars.iv = phi i64 [ 0, %for.cond1.preheader ], [ %indvars.iv.next, %for.body4 ]
%arrayidx6 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv26
%tmp = trunc i64 %indvars.iv26 to i32
store i32 %tmp, i32* %arrayidx6, align 4
%arrayidx10 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv.next27
%tmp1 = trunc i64 %indvars.iv to i32
store i32 %tmp1, i32* %arrayidx10, align 4
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%n.wide = zext i32 %n to i64
%exitcond = icmp ne i64 %indvars.iv.next, %n.wide
br i1 %exitcond, label %for.body4, label %for.cond.loopexit
}
; CHECK-LABEL: @interchange_11
; CHECK: entry:
; CHECK: br label %for.body4.preheader
; CHECK: for.cond1.preheader.preheader:
; CHECK: br label %for.cond1.preheader
; CHECK: for.cond.loopexit:
; CHECK: %exitcond28 = icmp ne i64 %indvars.iv.next27, 2
; CHECK: br i1 %exitcond28, label %for.cond1.preheader, label %for.body4.split
; CHECK: for.cond1.preheader:
; CHECK: %indvars.iv26 = phi i64 [ %indvars.iv.next27, %for.cond.loopexit ], [ 0, %for.cond1.preheader.preheader ]
; CHECK: %indvars.iv.next27 = add nuw nsw i64 %indvars.iv26, 1
; CHECK: br label %for.body4.split1
; CHECK: for.body4.preheader:
; CHECK: br label %for.body4
; CHECK: for.cond.cleanup:
; CHECK: ret void
; CHECK: for.body4:
; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %for.body4.split ], [ 0, %for.body4.preheader ]
; CHECK: br label %for.cond1.preheader.preheader
; CHECK: for.body4.split1:
; CHECK: %arrayidx6 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv26
; CHECK: %tmp = trunc i64 %indvars.iv26 to i32
; CHECK: store i32 %tmp, i32* %arrayidx6, align 4
; CHECK: br label %for.cond.loopexit
; CHECK: for.body4.split:
; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
; CHECK: %exitcond = icmp ne i64 %indvars.iv.next, %n.wide
; CHECK: br i1 %exitcond, label %for.body4, label %for.cond.cleanup