Revert LoopStrengthReduce.cpp to pre-r94061 for now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94123 91177308-0d34-0410-b5e6-96231b3b80d8

15 files changed, 37 insertions, 246 deletions

diff --git a/test/CodeGen/ARM/arm-negative-stride.ll b/test/CodeGen/ARM/arm-negative-stride.ll
index 52ab8717c1..72ec8efcc4 100644
--- a/test/CodeGen/ARM/arm-negative-stride.ll
+++ b/test/CodeGen/ARM/arm-negative-stride.ll
@@ -1,32 +1,7 @@
 ; RUN: llc < %s -march=arm | FileCheck %s
 
-; This loop is rewritten with an indvar which counts down, which
-; frees up a register from holding the trip count.
-
 define void @test(i32* %P, i32 %A, i32 %i) nounwind {
 entry:
-; CHECK: str r1, [{{r.*}}, +{{r.*}}, lsl #2]
-        icmp eq i32 %i, 0               ; <i1>:0 [#uses=1]
-        br i1 %0, label %return, label %bb
-
-bb:             ; preds = %bb, %entry
-        %indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb ]          ; <i32> [#uses=2]
-        %i_addr.09.0 = sub i32 %i, %indvar              ; <i32> [#uses=1]
-        %tmp2 = getelementptr i32* %P, i32 %i_addr.09.0         ; <i32*> [#uses=1]
-        store i32 %A, i32* %tmp2
-        %indvar.next = add i32 %indvar, 1               ; <i32> [#uses=2]
-        icmp eq i32 %indvar.next, %i            ; <i1>:1 [#uses=1]
-        br i1 %1, label %return, label %bb
-
-return:         ; preds = %bb, %entry
-        ret void
-}
-
-; This loop has a non-address use of the count-up indvar, so
-; it'll remain. Now the original store uses a negative-stride address.
-
-define void @test_with_forced_iv(i32* %P, i32 %A, i32 %i) nounwind {
-entry:
 ; CHECK: str r1, [{{r.*}}, -{{r.*}}, lsl #2]
         icmp eq i32 %i, 0               ; <i1>:0 [#uses=1]
         br i1 %0, label %return, label %bb
@@ -36,7 +11,6 @@ bb:             ; preds = %bb, %entry
         %i_addr.09.0 = sub i32 %i, %indvar              ; <i32> [#uses=1]
         %tmp2 = getelementptr i32* %P, i32 %i_addr.09.0         ; <i32*> [#uses=1]
         store i32 %A, i32* %tmp2
-        store i32 %indvar, i32* null
         %indvar.next = add i32 %indvar, 1               ; <i32> [#uses=2]
         icmp eq i32 %indvar.next, %i            ; <i1>:1 [#uses=1]
         br i1 %1, label %return, label %bb
diff --git a/test/CodeGen/ARM/lsr-code-insertion.ll b/test/CodeGen/ARM/lsr-code-insertion.ll
index 1bbb96deee..507ec2c7bd 100644
--- a/test/CodeGen/ARM/lsr-code-insertion.ll
+++ b/test/CodeGen/ARM/lsr-code-insertion.ll
@@ -1,5 +1,5 @@
-; RUN: llc < %s -stats |& grep {39.*Number of machine instrs printed}
-; RUN: llc < %s -stats |& not grep {.*Number of re-materialization}
+; RUN: llc < %s -stats |& grep {40.*Number of machine instrs printed}
+; RUN: llc < %s -stats |& grep {.*Number of re-materialization}
 ; This test really wants to check that the resultant "cond_true" block only 
 ; has a single store in it, and that cond_true55 only has code to materialize 
 ; the constant and do a store.  We do *not* want something like this:
diff --git a/test/CodeGen/ARM/remat.ll b/test/CodeGen/ARM/remat.ll
index 9072bcb762..9565c8bca6 100644
--- a/test/CodeGen/ARM/remat.ll
+++ b/test/CodeGen/ARM/remat.ll
@@ -1,4 +1,5 @@
-; RUN: llc < %s -mtriple=arm-apple-darwin -stats -info-output-file - | not grep "Number of re-materialization"
+; RUN: llc < %s -mtriple=arm-apple-darwin 
+; RUN: llc < %s -mtriple=arm-apple-darwin -stats -info-output-file - | grep "Number of re-materialization" | grep 3
 
 	%struct.CONTENTBOX = type { i32, i32, i32, i32, i32 }
 	%struct.LOCBOX = type { i32, i32, i32, i32 }
diff --git a/test/CodeGen/Thumb2/lsr-deficiency.ll b/test/CodeGen/Thumb2/lsr-deficiency.ll
index ac2cd34e4b..7b1b57a786 100644
--- a/test/CodeGen/Thumb2/lsr-deficiency.ll
+++ b/test/CodeGen/Thumb2/lsr-deficiency.ll
@@ -1,29 +1,25 @@
 ; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 -relocation-model=pic | FileCheck %s
 ; rdar://7387640
 
-; This now reduces to a single induction variable.
-
-; TODO: It still gets a GPR shuffle at the end of the loop
-; This is because something in instruction selection has decided
-; that comparing the pre-incremented value with zero is better
-; than comparing the post-incremented value with -4.
+; FIXME: We still need to rewrite array reference iv of stride -4 with loop
+; count iv of stride -1.
 
 @G = external global i32                          ; <i32*> [#uses=2]
 @array = external global i32*                     ; <i32**> [#uses=1]
 
 define arm_apcscc void @t() nounwind optsize {
 ; CHECK: t:
-; CHECK: mov.w r2, #1000
+; CHECK: mov.w r2, #4000
+; CHECK: movw r3, #1001
 entry:
   %.pre = load i32* @G, align 4                   ; <i32> [#uses=1]
   br label %bb
 
 bb:                                               ; preds = %bb, %entry
 ; CHECK: LBB1_1:
-; CHECK: cmp r2, #0
-; CHECK: sub.w r9, r2, #1
-; CHECK: mov r2, r9
-
+; CHECK: subs r3, #1
+; CHECK: cmp r3, #0
+; CHECK: sub.w r2, r2, #4
   %0 = phi i32 [ %.pre, %entry ], [ %3, %bb ]     ; <i32> [#uses=1]
   %indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
   %tmp5 = sub i32 1000, %indvar                   ; <i32> [#uses=1]
diff --git a/test/CodeGen/Thumb2/thumb2-ifcvt1.ll b/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
index 1d267565e0..71199abc57 100644
--- a/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
+++ b/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
@@ -1,6 +1,6 @@
 ; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
 
-define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
+define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) {
 ; CHECK: t1:
 ; CHECK: it ne
 ; CHECK: cmpne
@@ -20,12 +20,12 @@ cond_next:
 }
 
 ; FIXME: Check for # of unconditional branch after adding branch folding post ifcvt.
-define i32 @t2(i32 %a, i32 %b) nounwind {
+define i32 @t2(i32 %a, i32 %b) {
 entry:
 ; CHECK: t2:
-; CHECK: ite gt
-; CHECK: subgt
+; CHECK: ite le
 ; CHECK: suble
+; CHECK: subgt
 	%tmp1434 = icmp eq i32 %a, %b		; <i1> [#uses=1]
 	br i1 %tmp1434, label %bb17, label %bb.outer
 
@@ -60,14 +60,14 @@ bb17:		; preds = %cond_false, %cond_true, %entry
 
 @x = external global i32*		; <i32**> [#uses=1]
 
-define void @foo(i32 %a) nounwind {
+define void @foo(i32 %a) {
 entry:
 	%tmp = load i32** @x		; <i32*> [#uses=1]
 	store i32 %a, i32* %tmp
 	ret void
 }
 
-define void @t3(i32 %a, i32 %b) nounwind {
+define void @t3(i32 %a, i32 %b) {
 entry:
 ; CHECK: t3:
 ; CHECK: it lt
diff --git a/test/CodeGen/X86/2006-05-11-InstrSched.ll b/test/CodeGen/X86/2006-05-11-InstrSched.ll
index 56d6aa960e..bdbe713a29 100644
--- a/test/CodeGen/X86/2006-05-11-InstrSched.ll
+++ b/test/CodeGen/X86/2006-05-11-InstrSched.ll
@@ -1,5 +1,5 @@
 ; RUN: llc < %s -march=x86 -mattr=+sse2 -stats -realign-stack=0 |&\
-; RUN:     grep {asm-printer} | grep 34
+; RUN:     grep {asm-printer} | grep 31
 
 target datalayout = "e-p:32:32"
 define void @foo(i32* %mc, i32* %bp, i32* %ms, i32* %xmb, i32* %mpp, i32* %tpmm, i32* %ip, i32* %tpim, i32* %dpp, i32* %tpdm, i32* %bpi, i32 %M) nounwind {
@@ -40,7 +40,7 @@ cond_true:		; preds = %cond_true, %entry
 	%tmp137.upgrd.7 = bitcast i32* %tmp137 to <2 x i64>*		; <<2 x i64>*> [#uses=1]
 	store <2 x i64> %tmp131, <2 x i64>* %tmp137.upgrd.7
 	%tmp147 = add nsw i32 %tmp.10, 8		; <i32> [#uses=1]
-	%tmp.upgrd.8 = icmp ne i32 %tmp147, %M		; <i1> [#uses=1]
+	%tmp.upgrd.8 = icmp slt i32 %tmp147, %M		; <i1> [#uses=1]
 	%indvar.next = add i32 %indvar, 1		; <i32> [#uses=1]
 	br i1 %tmp.upgrd.8, label %cond_true, label %return
 
diff --git a/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll b/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll
index 8e315f4d80..721d4c945b 100644
--- a/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll
+++ b/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll
@@ -35,7 +35,7 @@ cond_next36.i:		; preds = %cond_next.i
 bb.i28.i:		; preds = %bb.i28.i, %cond_next36.i
 ; CHECK: %bb.i28.i
 ; CHECK: addl $2
-; CHECK: addl $-2
+; CHECK: addl $2
 	%j.0.reg2mem.0.i16.i = phi i32 [ 0, %cond_next36.i ], [ %indvar.next39.i, %bb.i28.i ]		; <i32> [#uses=2]
 	%din_addr.1.reg2mem.0.i17.i = phi double [ 0.000000e+00, %cond_next36.i ], [ %tmp16.i25.i, %bb.i28.i ]		; <double> [#uses=1]
 	%tmp1.i18.i = fptosi double %din_addr.1.reg2mem.0.i17.i to i32		; <i32> [#uses=2]
diff --git a/test/CodeGen/X86/iv-users-in-other-loops.ll b/test/CodeGen/X86/iv-users-in-other-loops.ll
index 0410bc0d9a..c695c29e06 100644
--- a/test/CodeGen/X86/iv-users-in-other-loops.ll
+++ b/test/CodeGen/X86/iv-users-in-other-loops.ll
@@ -1,11 +1,11 @@
 ; RUN: llc < %s -march=x86-64 -o %t
-; RUN: not grep inc %t
+; RUN: grep inc %t | count 1
 ; RUN: grep dec %t | count 2
-; RUN: grep addq %t | count 10
+; RUN: grep addq %t | count 13
 ; RUN: not grep addb %t
 ; RUN: grep leaq %t | count 9
-; RUN: grep leal %t | count 2
-; RUN: grep movq %t | count 10
+; RUN: grep leal %t | count 3
+; RUN: grep movq %t | count 5
 
 ; IV users in each of the loops from other loops shouldn't cause LSR
 ; to insert new induction variables. Previously it would create a
diff --git a/test/CodeGen/X86/loop-strength-reduce4.ll b/test/CodeGen/X86/loop-strength-reduce4.ll
index 6c0eb8c0df..07e46eca75 100644
--- a/test/CodeGen/X86/loop-strength-reduce4.ll
+++ b/test/CodeGen/X86/loop-strength-reduce4.ll
@@ -1,19 +1,5 @@
-; RUN: llc < %s -march=x86 -relocation-model=static -mtriple=i686-apple-darwin | FileCheck %s -check-prefix=STATIC
-; RUN: llc < %s -march=x86 -relocation-model=pic | FileCheck %s -check-prefix=PIC
-
-; By starting the IV at -64 instead of 0, a cmp is eliminated,
-; as the flags from the add can be used directly.
-
-; STATIC: movl    $-64, %ecx
-
-; STATIC: movl    %eax, _state+76(%ecx)
-; STATIC: addl    $16, %ecx
-; STATIC: jne
-
-; In PIC mode the symbol can't be folded, so the change-compare-stride
-; trick applies.
-
-; PIC: cmpl $64
+; RUN: llc < %s -march=x86 | grep cmp | grep 64
+; RUN: llc < %s -march=x86 | not grep inc
 
 @state = external global [0 x i32]		; <[0 x i32]*> [#uses=4]
 @S = external global [0 x i32]		; <[0 x i32]*> [#uses=4]
diff --git a/test/CodeGen/X86/loop-strength-reduce8.ll b/test/CodeGen/X86/loop-strength-reduce8.ll
index 6b2247d1d6..e14cd8a99e 100644
--- a/test/CodeGen/X86/loop-strength-reduce8.ll
+++ b/test/CodeGen/X86/loop-strength-reduce8.ll
@@ -1,10 +1,4 @@
-; RUN: llc < %s -mtriple=i386-apple-darwin | FileCheck %s
-
-; CHECK: leal 16(%eax), %edx
-; CHECK: align
-; CHECK: addl    $4, %edx
-; CHECK: decl    %ecx
-; CHECK: jne     LBB1_2
+; RUN: llc < %s -mtriple=i386-apple-darwin | grep leal | not grep 16
 
 	%struct.CUMULATIVE_ARGS = type { i32, i32, i32, i32, i32, i32, i32 }
 	%struct.bitmap_element = type { %struct.bitmap_element*, %struct.bitmap_element*, i32, [2 x i64] }
diff --git a/test/CodeGen/X86/lsr-reuse.ll b/test/CodeGen/X86/lsr-reuse.ll
deleted file mode 100644
index a1919bab38..0000000000
--- a/test/CodeGen/X86/lsr-reuse.ll
+++ /dev/null
@@ -1,159 +0,0 @@
-; RUN: llc < %s -march=x86-64 | FileCheck %s
-target datalayout = "e-p:64:64:64"
-target triple = "x86_64-unknown-unknown"
-
-; Full strength reduction reduces register pressure from 5 to 4 here.
-
-; CHECK: full_me:
-; CHECK: movsd   (%rsi), %xmm0
-; CHECK: mulsd   (%rdx), %xmm0
-; CHECK: movsd   %xmm0, (%rdi)
-; CHECK: addq    $8, %rsi
-; CHECK: addq    $8, %rdx
-; CHECK: addq    $8, %rdi
-; CHECK: decq    %rcx
-; CHECK: jne
-
-define void @full_me(double* nocapture %A, double* nocapture %B, double* nocapture %C, i64 %n) nounwind {
-entry:
-  %t0 = icmp sgt i64 %n, 0
-  br i1 %t0, label %loop, label %return
-
-loop:
-  %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
-  %Ai = getelementptr inbounds double* %A, i64 %i
-  %Bi = getelementptr inbounds double* %B, i64 %i
-  %Ci = getelementptr inbounds double* %C, i64 %i
-  %t1 = load double* %Bi
-  %t2 = load double* %Ci
-  %m = fmul double %t1, %t2
-  store double %m, double* %Ai
-  %i.next = add nsw i64 %i, 1
-  %exitcond = icmp eq i64 %i.next, %n
-  br i1 %exitcond, label %return, label %loop
-
-return:
-  ret void
-}
-
-; In this test, the counting IV exit value is used, so full strength reduction
-; would not reduce register pressure. IndVarSimplify ought to simplify such
-; cases away, but it's useful here to verify that LSR's register pressure
-; heuristics are working as expected.
-
-; CHECK: count_me_0:
-; CHECK: movsd   (%rsi,%rax,8), %xmm0
-; CHECK: mulsd   (%rdx,%rax,8), %xmm0
-; CHECK: movsd   %xmm0, (%rdi,%rax,8)
-; CHECK: incq    %rax
-; CHECK: cmpq    %rax, %rcx
-; CHECK: jne
-
-define i64 @count_me_0(double* nocapture %A, double* nocapture %B, double* nocapture %C, i64 %n) nounwind {
-entry:
-  %t0 = icmp sgt i64 %n, 0
-  br i1 %t0, label %loop, label %return
-
-loop:
-  %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
-  %Ai = getelementptr inbounds double* %A, i64 %i
-  %Bi = getelementptr inbounds double* %B, i64 %i
-  %Ci = getelementptr inbounds double* %C, i64 %i
-  %t1 = load double* %Bi
-  %t2 = load double* %Ci
-  %m = fmul double %t1, %t2
-  store double %m, double* %Ai
-  %i.next = add nsw i64 %i, 1
-  %exitcond = icmp eq i64 %i.next, %n
-  br i1 %exitcond, label %return, label %loop
-
-return:
-  %q = phi i64 [ 0, %entry ], [ %i.next, %loop ]
-  ret i64 %q
-}
-
-; In this test, the trip count value is used, so full strength reduction
-; would not reduce register pressure.
-; (though it would reduce register pressure inside the loop...)
-
-; CHECK: count_me_1:
-; CHECK: movsd   (%rsi,%rax,8), %xmm0
-; CHECK: mulsd   (%rdx,%rax,8), %xmm0
-; CHECK: movsd   %xmm0, (%rdi,%rax,8)
-; CHECK: incq    %rax
-; CHECK: cmpq    %rax, %rcx
-; CHECK: jne
-
-define i64 @count_me_1(double* nocapture %A, double* nocapture %B, double* nocapture %C, i64 %n) nounwind {
-entry:
-  %t0 = icmp sgt i64 %n, 0
-  br i1 %t0, label %loop, label %return
-
-loop:
-  %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
-  %Ai = getelementptr inbounds double* %A, i64 %i
-  %Bi = getelementptr inbounds double* %B, i64 %i
-  %Ci = getelementptr inbounds double* %C, i64 %i
-  %t1 = load double* %Bi
-  %t2 = load double* %Ci
-  %m = fmul double %t1, %t2
-  store double %m, double* %Ai
-  %i.next = add nsw i64 %i, 1
-  %exitcond = icmp eq i64 %i.next, %n
-  br i1 %exitcond, label %return, label %loop
-
-return:
-  %q = phi i64 [ 0, %entry ], [ %n, %loop ]
-  ret i64 %q
-}
-
-; This should be fully strength-reduced to reduce register pressure, however
-; the current heuristics get distracted by all the reuse with the stride-1
-; induction variable first.
-
-; But even so, be clever and start the stride-1 variable at a non-zero value
-; to eliminate an in-loop immediate value.
-
-; CHECK: count_me_2:
-; CHECK: movl    $5, %eax
-; CHECK: align
-; CHECK: BB4_1:
-; CHECK: movsd   (%rdi,%rax,8), %xmm0
-; CHECK: addsd   (%rsi,%rax,8), %xmm0
-; CHECK: movsd   %xmm0, (%rdx,%rax,8)
-; CHECK: movsd   40(%rdi,%rax,8), %xmm0
-; CHECK: addsd   40(%rsi,%rax,8), %xmm0
-; CHECK: movsd   %xmm0, 40(%rdx,%rax,8)
-; CHECK: incq    %rax
-; CHECK: cmpq    $5005, %rax
-; CHECK: jne
-
-define void @count_me_2(double* nocapture %A, double* nocapture %B, double* nocapture %C) nounwind {
-entry:
-  br label %loop
-
-loop:
-  %i = phi i64 [ 0, %entry ], [ %i.next, %loop ]
-  %i5 = add i64 %i, 5
-  %Ai = getelementptr double* %A, i64 %i5
-  %t2 = load double* %Ai
-  %Bi = getelementptr double* %B, i64 %i5
-  %t4 = load double* %Bi
-  %t5 = fadd double %t2, %t4
-  %Ci = getelementptr double* %C, i64 %i5
-  store double %t5, double* %Ci
-  %i10 = add i64 %i, 10
-  %Ai10 = getelementptr double* %A, i64 %i10
-  %t9 = load double* %Ai10
-  %Bi10 = getelementptr double* %B, i64 %i10
-  %t11 = load double* %Bi10
-  %t12 = fadd double %t9, %t11
-  %Ci10 = getelementptr double* %C, i64 %i10
-  store double %t12, double* %Ci10
-  %i.next = add i64 %i, 1
-  %exitcond = icmp eq i64 %i.next, 5000
-  br i1 %exitcond, label %return, label %loop
-
-return:
-  ret void
-}
diff --git a/test/CodeGen/X86/masked-iv-safe.ll b/test/CodeGen/X86/masked-iv-safe.ll
index 7111d687ed..bc493bd8f7 100644
--- a/test/CodeGen/X86/masked-iv-safe.ll
+++ b/test/CodeGen/X86/masked-iv-safe.ll
@@ -4,9 +4,9 @@
 ; RUN: not grep sar %t
 ; RUN: not grep shl %t
 ; RUN: grep add %t | count 2
-; RUN: grep inc %t | count 3
+; RUN: grep inc %t | count 4
 ; RUN: grep dec %t | count 2
-; RUN: grep lea %t | count 3
+; RUN: grep lea %t | count 2
 
 ; Optimize away zext-inreg and sext-inreg on the loop induction
 ; variable using trip-count information.
@@ -127,9 +127,6 @@ return:
 	ret void
 }
 
-; TODO: If we could handle all the loads and stores as post-inc users, we could
-; use {-1,+,1} in the induction variable register, and we'd get another inc,
-; one fewer add, and a comparison with zero.
 define void @another_count_up(double* %d, i64 %n) nounwind {
 entry:
 	br label %loop
diff --git a/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll b/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
index 99cb8569b3..7c7a21c013 100644
--- a/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
+++ b/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
@@ -1,4 +1,5 @@
-; RUN: llc -march=x86-64 < %s -o - | grep {cmpl	\\$\[1\], %}
+; RUN: opt < %s -loop-reduce -S | grep ugt
+; PR2535
 
 @.str = internal constant [4 x i8] c"%d\0A\00"
 
@@ -15,7 +16,7 @@ forbody:
         %add166 = or i32 %mul15, 1              ; <i32> [#uses=1] *
         call i32 (i8*, ...)* @printf( i8* noalias  getelementptr ([4 x i8]* @.str, i32 0, i32 0), i32 %add166 ) nounwind
         %inc = add i32 %i.0, 1          ; <i32> [#uses=3]
-        %cmp = icmp ne i32 %inc, 1027          ; <i1> [#uses=1]
+        %cmp = icmp ult i32 %inc, 1027          ; <i1> [#uses=1]
         br i1 %cmp, label %forbody, label %afterfor
 
 afterfor:               ; preds = %forcond
diff --git a/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll b/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
index d9abc8ba66..36941ad6d3 100644
--- a/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
+++ b/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
@@ -1,9 +1,10 @@
-; RUN: llc < %s -o - | grep {testl	%ecx, %ecx}
+; RUN: llc %s -o - --x86-asm-syntax=att | grep {cmpl	\$4}
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
 target triple = "x86_64-apple-darwin9"
 
-; The comparison happens before the relevant use, but it can still be rewritten
-; to compare with zero.
+; This is like change-compare-stride-trickiness-1.ll except the comparison
+; happens before the relevant use, so the comparison stride can't be
+; easily changed.
 
 define void @foo() nounwind {
 entry:
diff --git a/test/Transforms/LoopStrengthReduce/count-to-zero.ll b/test/Transforms/LoopStrengthReduce/count-to-zero.ll
index feb79f8a0c..8cc3b5c103 100644
--- a/test/Transforms/LoopStrengthReduce/count-to-zero.ll
+++ b/test/Transforms/LoopStrengthReduce/count-to-zero.ll
@@ -19,7 +19,7 @@ bb3:                                              ; preds = %bb1
   %tmp4 = add i32 %c_addr.1, -1                   ; <i32> [#uses=1]
   %c_addr.1.be = select i1 %tmp2, i32 %tmp3, i32 %tmp4 ; <i32> [#uses=1]
   %indvar.next = add i32 %indvar, 1               ; <i32> [#uses=1]
-; CHECK: add i32 %lsr.iv, -1
+; CHECK: sub i32 %lsr.iv, 1
   br label %bb6
 
 bb6:                                              ; preds = %bb3, %entry