From: Dan Gohman <gohman@apple.com>
Date: Wed, 27 May 2009 20:00:18 +0000 (+0000)
Subject: In ChangeCompareStride, when the stride to be reused is truncated to
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=ead28bd04bf42cdf8c29d12fa4c0f9d29a4c58cd;p=oota-llvm.git

In ChangeCompareStride, when the stride to be reused is truncated to
a smaller type, promoted its offset back up to the type of the new
comparison. This fixes PR4222.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72493 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index adfa5272a9c..834a95d7318 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2005,11 +2005,16 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
         ConstantInt *CI = ConstantInt::get(NewCmpIntTy, NewCmpVal);
         NewCmpRHS = ConstantExpr::getIntToPtr(CI, NewCmpTy);
       }
+      NewOffset = CondUse->getOffset();
+      if (CondUse->isSigned())
+        NewOffset = SE->getNoopOrSignExtend(CondUse->getOffset(), NewCmpTy);
+      else
+        NewOffset = SE->getNoopOrZeroExtend(CondUse->getOffset(), NewCmpTy);
       NewOffset = TyBits == NewTyBits
-        ? SE->getMulExpr(CondUse->getOffset(),
+        ? SE->getMulExpr(NewOffset,
                          SE->getConstant(ConstantInt::get(CmpTy, Scale)))
         : SE->getConstant(ConstantInt::get(NewCmpIntTy,
-          cast<SCEVConstant>(CondUse->getOffset())->getValue()
+          cast<SCEVConstant>(NewOffset)->getValue()
             ->getSExtValue()*Scale));
       break;
     }
diff --git a/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll b/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll
new file mode 100644
index 00000000000..e3cb3a50953
--- /dev/null
+++ b/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-2.ll
@@ -0,0 +1,33 @@
+; RUN: llvm-as < %s | llc
+; PR4222
+
+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-f80:128:128"
+target triple = "x86_64-pc-linux-gnu"
+module asm ".ident\09\22$FreeBSD: head/sys/amd64/amd64/minidump_machdep.c 184499 2008-10-31 10:11:35Z kib $\22"
+	%struct.dumperinfo = type <{ i32 (i8*, i8*, i64, i64, i64)*, i8*, i32, i32, i64, i64 }>
+
+define void @minidumpsys(%struct.dumperinfo* %di) nounwind {
+entry:
+	br label %if.end
+
+if.end:		; preds = %if.end52, %entry
+	br label %for.cond.i.preheader
+
+for.cond.i.preheader:		; preds = %if.end52, %if.end
+	%indvar688 = phi i64 [ 0, %if.end ], [ %indvar.next689, %if.end52 ]		; <i64> [#uses=3]
+	%tmp690 = shl i64 %indvar688, 12		; <i64> [#uses=1]
+	%pa.0642 = add i64 %tmp690, 0		; <i64> [#uses=1]
+	%indvar688703 = trunc i64 %indvar688 to i32		; <i32> [#uses=1]
+	%tmp692693 = add i32 %indvar688703, 1		; <i32> [#uses=1]
+	%phitmp = sext i32 %tmp692693 to i64		; <i64> [#uses=1]
+	br i1 false, label %if.end52, label %land.lhs.true.i
+
+land.lhs.true.i:		; preds = %for.cond.i.preheader
+	%shr2.i = lshr i64 %pa.0642, 18		; <i64> [#uses=0]
+	unreachable
+
+if.end52:		; preds = %for.cond.i.preheader
+	%phitmp654 = icmp ult i64 %phitmp, 512		; <i1> [#uses=1]
+	%indvar.next689 = add i64 %indvar688, 1		; <i64> [#uses=1]
+	br i1 %phitmp654, label %for.cond.i.preheader, label %if.end
+}