Revert some changes that were made to fix PR20680.

This re-lands change r230921.  r230921 was reverted because it broke a
clang test; a checkin fixing the clang test will be commited shortly.

Summary:
As far as I can tell, the real bug causing the issue was fixed in
r230533.  SCEVExpander should mark an increment operation as nuw or nsw
only if it can *prove* that the operation does not overflow.  There
shouldn't be any situation where we have to do something different
because of no-wrap flags generated by SCEVExpander.

Revert "IndVarSimplify: Allow LFTR to fire more often"

This reverts commit 1ade0f0faa98877b688e0b9da58e876052c1e04e (SVN: 222213).

Revert "IndVarSimplify: Don't let LFTR compare against a poison value"

This reverts commit c0f2b8b528d8a37b0a1522aae90af649d6357eb5 (SVN: 217102).

Reviewers: majnemer, atrick, spatel

Differential Revision: http://reviews.llvm.org/D7979

llvm-svn: 231018

3 files changed, 11 insertions, 19 deletions

diff --git a/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll b/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll
index 75eaf918bcf..f1d1139aef8 100644
--- a/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll
+++ b/llvm/test/Transforms/IndVarSimplify/2011-10-27-lftrnull.ll
@@ -6,7 +6,7 @@ target triple = "thumbv7-apple-darwin"
 
 ; CHECK-LABEL: @test(
 ; CHECK: if.end.i126:
-; CHECK: %exitcond = icmp ne i8* %destYPixelPtr.010.i, getelementptr (i8* null, i32 undef)
+; CHECK: %exitcond = icmp ne i8* %incdec.ptr.i, getelementptr (i8* null, i32 undef)
 define void @test() nounwind {
 entry:
   br label %while.cond
diff --git a/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll b/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll
index b23e08dfad7..feb4b35a20a 100644
--- a/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll
+++ b/llvm/test/Transforms/IndVarSimplify/lftr-address-space-pointers.ll
@@ -11,7 +11,7 @@ entry:
   br i1 %cmp1, label %for.body, label %for.end
 
 ; Make sure the added GEP has the right index type
-; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(2)* %base, i8
+; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(2)* %base, i8 %0
 
 ; CHECK: for.body:
 ; CHECK: phi i8 addrspace(2)*
@@ -43,7 +43,7 @@ entry:
   br i1 %cmp1, label %for.body, label %for.end
 
 ; Make sure the added GEP has the right index type
-; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(3)* %base, i16
+; CHECK: %lftr.limit = getelementptr i8, i8 addrspace(3)* %base, i16 %0
 
 ; CHECK: for.body:
 ; CHECK: phi i8 addrspace(3)*
diff --git a/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll b/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll
index befbb9e3f15..b4e1fdef488 100644
--- a/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll
+++ b/llvm/test/Transforms/IndVarSimplify/lftr-reuse.ll
@@ -82,23 +82,15 @@ exit:
 ; Perform LFTR without generating extra preheader code.
 define void @guardedloop([0 x double]* %matrix, [0 x double]* %vector,
                          i32 %irow, i32 %ilead) nounwind {
-; CHECK-LABEL: @guardedloop(
-; CHECK-LABEL: entry:
-; CHECK-NEXT: %[[cmp:.*]] = icmp slt i32 1, %irow
-; CHECK-NEXT: br i1 %[[cmp]], label %[[loop_preheader:.*]], label %[[return:.*]]
-
-; CHECK: [[loop_preheader]]:
-; CHECK-NEXT: %[[sext:.*]] = sext i32 %ilead to i64
-; CHECK-NEXT: %[[add:.*]] = add i32 %irow, -1
-; CHECK-NEXT: br label %[[loop:.*]]
-
-; CHECK: [[loop]]:
-; CHECK-NEXT: %[[indvars_iv2:.*]] = phi i64
-; CHECK-NEXT: phi i64
+; CHECK: entry:
+; CHECK-NOT: zext
+; CHECK-NOT: add
+; CHECK: loop:
+; CHECK: phi i64
+; CHECK: phi i64
 ; CHECK-NOT: phi
-; CHECK: %[[lftr_wideiv:.*]] = trunc i64 %[[indvars_iv2]] to i32
-; CHECK-NEXT: %[[exitcond:.*]] = icmp ne i32 %[[lftr_wideiv]], %[[add]]
-; CHECK-NEXT: br i1 %[[exitcond]], label %[[loop]], label
+; CHECK: icmp ne
+; CHECK: br i1
 entry:
   %cmp = icmp slt i32 1, %irow
   br i1 %cmp, label %loop, label %return