[SimplifyIndVars] Eliminate redundant truncs

This patch adds logic to deal with the following constructions:

  %iv = phi i64 ...
  %trunc = trunc i64 %iv to i32
  %cmp = icmp <pred> i32 %trunc, %invariant

Replacing it with
  %iv = phi i64 ...
  %cmp = icmp <pred> i64 %iv, sext/zext(%invariant)

In case if it is legal. Specifically, if `%iv` has signed comparison users, it is
required that `sext(trunc(%iv)) == %iv`, and if it has unsigned comparison
uses then we require `zext(trunc(%iv)) == %iv`. The current implementation
bails if `%trunc` has other uses than `icmp`, but in theory we can handle more
cases here (e.g. if the user of trunc is bitcast).

Differential Revision: https://reviews.llvm.org/D47928
Reviewed By: reames

llvm-svn: 335020

3 files changed, 496 insertions, 3 deletions

diff --git a/llvm/test/Transforms/IndVarSimplify/ada-loops.ll b/llvm/test/Transforms/IndVarSimplify/ada-loops.ll
index e452f03bed9..4cc7cb65813 100644
--- a/llvm/test/Transforms/IndVarSimplify/ada-loops.ll
+++ b/llvm/test/Transforms/IndVarSimplify/ada-loops.ll
@@ -10,12 +10,17 @@
 ; don't check that phis are "folded together" because that is a job
 ; for loop strength reduction. But indvars must remove sext, zext, and add i8.
 ;
-; CHECK-NOT: {{sext|zext|add i8}}
 
 ; ModuleID = 'ada.bc'
 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-n8:16:32"
 target triple = "i686-pc-linux-gnu"
 
+; CHECK-LABEL: @kinds__sbytezero
+; CHECK:         bb.thread:
+; CHECK:         sext
+; CHECK:         bb:
+; CHECK-NOT:     {{sext i8|zext i8|add i8|trunc}}
+
 define void @kinds__sbytezero([256 x i32]* nocapture %a) nounwind {
 bb.thread:
 	%tmp46 = getelementptr [256 x i32], [256 x i32]* %a, i32 0, i32 0		; <i32*> [#uses=1]
@@ -36,6 +41,8 @@ return:		; preds = %bb
 	ret void
 }
 
+; CHECK-LABEL: @kinds__ubytezero
+
 define void @kinds__ubytezero([256 x i32]* nocapture %a) nounwind {
 bb.thread:
 	%tmp35 = getelementptr [256 x i32], [256 x i32]* %a, i32 0, i32 0		; <i32*> [#uses=1]
diff --git a/llvm/test/Transforms/IndVarSimplify/eliminate-trunc.ll b/llvm/test/Transforms/IndVarSimplify/eliminate-trunc.ll
new file mode 100644
index 00000000000..660d8e507e9
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/eliminate-trunc.ll
@@ -0,0 +1,486 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -indvars -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; General case: without extra knowledge, trunc cannot be eliminated.
+define void @test_00(i64 %start, i32 %n) {
+;
+; CHECK-LABEL: @test_00(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT:    [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+
+define void @test_01(i32 %n) {
+;
+; CHECK-LABEL: @test_01(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Max value at which we can eliminate trunc: SINT_MAX - 1.
+define void @test_02(i32 %n) {
+;
+; CHECK-LABEL: @test_02(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 2147483646, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 2147483646, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; If we start from SINT_MAX then the predicate is always false.
+define void @test_03(i32 %n) {
+;
+; CHECK-LABEL: @test_03(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    br i1 false, label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [2147483647, %entry], [%iv.next, %loop]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Minimum value at which we can apply the transform: SINT_MIN + 1.
+define void @test_04(i32 %n) {
+;
+; CHECK-LABEL: @test_04(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ -2147483647, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ -2147483647, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; FIXME: Harmful LFTR should be thrown away.
+define void @test_05(i32 %n) {
+;
+; CHECK-LABEL: @test_05(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[N:%.*]], 1
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ -2147483648, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[LFTR_WIDEIV:%.*]] = trunc i64 [[IV_NEXT]] to i32
+; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp ne i32 [[LFTR_WIDEIV]], [[TMP0]]
+; CHECK-NEXT:    br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ -2147483648, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Trunc changes the actual value of the IV, so it is invalid to remove it: SINT_MIN - 1.
+define void @test_06(i32 %n) {
+;
+; CHECK-LABEL: @test_06(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ -2147483649, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ -2147483649, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; General case: without extra knowledge, trunc cannot be eliminated.
+define void @test_00_unsigned(i64 %start, i32 %n) {
+; CHECK-LABEL: @test_00_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT:    [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; FIXME: Harmful LFTR should be thrown away.
+define void @test_01_unsigned(i32 %n) {
+; CHECK-LABEL: @test_01_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[N:%.*]], 1
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[LFTR_WIDEIV:%.*]] = trunc i64 [[IV_NEXT]] to i32
+; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp ne i32 [[LFTR_WIDEIV]], [[TMP0]]
+; CHECK-NEXT:    br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Max value at which we can eliminate trunc: UINT_MAX - 1.
+define void @test_02_unsigned(i32 %n) {
+; CHECK-LABEL: @test_02_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 4294967294, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 4294967294, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; If we start from UINT_MAX then the predicate is always false.
+define void @test_03_unsigned(i32 %n) {
+; CHECK-LABEL: @test_03_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    br i1 false, label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 4294967295, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Minimum value at which we can apply the transform: UINT_MIN.
+define void @test_04_unsigned(i32 %n) {
+; CHECK-LABEL: @test_04_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[N:%.*]], 1
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[LFTR_WIDEIV:%.*]] = trunc i64 [[IV_NEXT]] to i32
+; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp ne i32 [[LFTR_WIDEIV]], [[TMP0]]
+; CHECK-NEXT:    br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Start from 1.
+define void @test_05_unsigned(i32 %n) {
+; CHECK-LABEL: @test_05_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Trunc changes the actual value of the IV, so it is invalid to remove it: UINT_MIN - 1.
+define void @test_06_unsigned(i32 %n) {
+; CHECK-LABEL: @test_06_unsigned(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ -1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ -1, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ult i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Do not eliminate trunc if it is used by something different from icmp.
+define void @test_07(i32* %p, i32 %n) {
+; CHECK-LABEL: @test_07(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT:    store i32 [[NARROW_IV]], i32* [[P:%.*]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  store i32 %narrow.iv, i32* %p
+  %cmp = icmp slt i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Check that we can eliminate both signed and unsigned compare.
+define void @test_08(i32 %n) {
+; CHECK-LABEL: @test_08(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    [[SEXT:%.*]] = sext i32 [[N]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    [[CMP:%.*]] = and i1 [[TMP0]], [[TMP1]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp1 = icmp slt i32 %narrow.iv, %n
+  %cmp2 = icmp ult i32 %narrow.iv, %n
+  %cmp = and i1 %cmp1, %cmp2
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Widen NE as unsigned.
+define void @test_09(i32 %n) {
+; CHECK-LABEL: @test_09(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %cmp = icmp ne i32 %narrow.iv, %n
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
+
+; Widen NE as signed.
+define void @test_10(i32 %n) {
+; CHECK-LABEL: @test_10(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ -100, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i64 [[IV]], [[SEXT]]
+; CHECK-NEXT:    [[NEGCMP:%.*]] = icmp slt i64 [[IV]], -10
+; CHECK-NEXT:    [[CMP:%.*]] = and i1 [[TMP0]], [[NEGCMP]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+loop:
+  %iv = phi i64 [ -100, %entry ], [ %iv.next, %loop ]
+  %iv.next = add i64 %iv, 1
+  %narrow.iv = trunc i64 %iv to i32
+  %trunccmp = icmp ne i32 %narrow.iv, %n
+  %negcmp = icmp slt i64 %iv, -10
+  %cmp = and i1 %trunccmp, %negcmp
+  br i1 %cmp, label %loop, label %exit
+exit:
+  ret void
+}
diff --git a/llvm/test/Transforms/IndVarSimplify/widen-loop-comp.ll b/llvm/test/Transforms/IndVarSimplify/widen-loop-comp.ll
index 2d24cd732ce..5630c5dd075 100644
--- a/llvm/test/Transforms/IndVarSimplify/widen-loop-comp.ll
+++ b/llvm/test/Transforms/IndVarSimplify/widen-loop-comp.ll
@@ -332,12 +332,12 @@ define i32 @test10(i32 %v) {
   br label %loop
 
  loop:
+; CHECK: [[WIDE_V:%[a-z0-9]+]] = sext i32 %v to i64
 ; CHECK: loop:
 ; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %loop ], [ 0, %entry ]
 ; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
 ; CHECK: [[MUL:%[a-z0-9]+]] = mul nsw i64 %indvars.iv, -1
-; CHECK: [[MUL_TRUNC:%[a-z0-9]+]] = trunc i64 [[MUL]] to i32
-; CHECK: [[CMP:%[a-z0-9]+]] = icmp eq i32 [[MUL_TRUNC]], %v
+; CHECK: [[CMP:%[a-z0-9]+]] = icmp eq i64 [[MUL]], [[WIDE_V]]
 ; CHECK: call void @consume.i1(i1 [[CMP]])
 
   %i = phi i32 [ 0, %entry ], [ %i.inc, %loop ]