From 360026f07fcf35eee9fcfbf7b9c1afda41d4b148 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Tue, 18 May 2010 23:48:08 +0000
Subject: [PATCH] Fix the predicate which checks for non-sensical formulae
 which have constants in registers which partially cancel out their immediate
 fields.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104088 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LoopStrengthReduce.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 6bab98bab77..921f0b9638b 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2572,10 +2572,11 @@ void LSRInstance::GenerateCrossUseConstantOffsets() {
                J = NewF.BaseRegs.begin(), JE = NewF.BaseRegs.end();
                J != JE; ++J)
             if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*J))
-              if (C->getValue()->getValue().isNegative() !=
-                    (NewF.AM.BaseOffs < 0) &&
-                  C->getValue()->getValue().abs()
-                    .ule(abs64(NewF.AM.BaseOffs)))
+              if ((C->getValue()->getValue() + NewF.AM.BaseOffs).abs().slt(
+                   abs64(NewF.AM.BaseOffs)) &&
+                  (C->getValue()->getValue() +
+                   NewF.AM.BaseOffs).countTrailingZeros() >=
+                   CountTrailingZeros_64(NewF.AM.BaseOffs))
                 goto skip_formula;
 
           // Ok, looks good.