[llvm] r207853 - [GVN] Pass the phi-translated address of a load instead of the untranslated

[Akira Hatanaka]

Author: ahatanak
Date: Fri May  2 12:59:17 2014
New Revision: 207853

URL: http://llvm.org/viewvc/llvm-project?rev=207853&view=rev
Log:
[GVN] Pass the phi-translated address of a load instead of the untranslated
address to AnalyzeLoadFromClobberingLoad. This fixes a bug in load-PRE where
PRE is applied to a load that is not partially redundant.

<rdar://problem/16638765>.


Added:
    llvm/trunk/test/Transforms/GVN/load-pre-nonlocal.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/GVN.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=207853&r1=207852&r2=207853&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Fri May  2 12:59:17 2014
@@ -1421,8 +1421,7 @@ void GVN::AnalyzeLoadAvailability(LoadIn
         // If this is a clobber and L is the first instruction in its block, then
         // we have the first instruction in the entry block.
         if (DepLI != LI && Address && DL) {
-          int Offset = AnalyzeLoadFromClobberingLoad(LI->getType(),
-                                                     LI->getPointerOperand(),
+          int Offset = AnalyzeLoadFromClobberingLoad(LI->getType(), Address,
                                                      DepLI, *DL);
 
           if (Offset != -1) {

Added: llvm/trunk/test/Transforms/GVN/load-pre-nonlocal.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GVN/load-pre-nonlocal.ll?rev=207853&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/GVN/load-pre-nonlocal.ll (added)
+++ llvm/trunk/test/Transforms/GVN/load-pre-nonlocal.ll Fri May  2 12:59:17 2014
@@ -0,0 +1,87 @@
+; RUN: opt -S -o - -basicaa -domtree -gvn %s | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct.S1 = type { i32, i32 }
+
+ at a2 = common global i32* null, align 8
+ at a = common global i32* null, align 8
+ at s1 = common global %struct.S1 zeroinitializer, align 8
+
+; Check that GVN doesn't determine %2 is partially redundant.
+
+; CHECK-LABEL: define i32 @volatile_load
+; CHECK: for.body:
+; CHECK: %2 = load i32*
+; CHECK: %3 = load volatile i32*
+; CHECK: for.cond.for.end_crit_edge:
+
+define i32 @volatile_load(i32 %n) {
+entry:
+  %cmp6 = icmp sgt i32 %n, 0
+  br i1 %cmp6, label %for.body.lr.ph, label %for.end
+
+for.body.lr.ph:
+  %0 = load i32** @a2, align 8, !tbaa !1
+  %1 = load i32** @a, align 8, !tbaa !1
+  br label %for.body
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body ]
+  %s.09 = phi i32 [ 0, %for.body.lr.ph ], [ %add, %for.body ]
+  %p.08 = phi i32* [ %0, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
+  %2 = load i32* %p.08, align 4, !tbaa !5
+  %arrayidx = getelementptr inbounds i32* %1, i64 %indvars.iv
+  store i32 %2, i32* %arrayidx, align 4, !tbaa !5
+  %3 = load volatile i32* %p.08, align 4, !tbaa !5
+  %add = add nsw i32 %3, %s.09
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %incdec.ptr = getelementptr inbounds i32* %p.08, i64 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp ne i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
+
+for.cond.for.end_crit_edge:
+  %add.lcssa = phi i32 [ %add, %for.body ]
+  br label %for.end
+
+for.end:
+  %s.0.lcssa = phi i32 [ %add.lcssa, %for.cond.for.end_crit_edge ], [ 0, %entry ]
+  ret i32 %s.0.lcssa
+}
+
+; %1 is partially redundant if %0 can be widened to a 64-bit load.
+
+; CHECK-LABEL: define i32 @overaligned_load
+; CHECK: if.end:
+; CHECK-NOT: %1 = load i32*
+
+define i32 @overaligned_load(i32 %a, i32* nocapture %b) {
+entry:
+  %cmp = icmp sgt i32 %a, 0
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  %0 = load i32* getelementptr inbounds (%struct.S1* @s1, i64 0, i32 0), align 8, !tbaa !5
+  br label %if.end
+
+if.else:
+  %arrayidx = getelementptr inbounds i32* %b, i64 2
+  store i32 10, i32* %arrayidx, align 4, !tbaa !5
+  br label %if.end
+
+if.end:
+  %i.0 = phi i32 [ %0, %if.then ], [ 0, %if.else ]
+  %p.0 = phi i32* [ getelementptr inbounds (%struct.S1* @s1, i64 0, i32 0), %if.then ], [ %b, %if.else ]
+  %add.ptr = getelementptr inbounds i32* %p.0, i64 1
+  %1 = load i32* %add.ptr, align 4, !tbaa !5
+  %add1 = add nsw i32 %1, %i.0
+  ret i32 %add1
+}
+
+!1 = metadata !{metadata !2, metadata !2, i64 0}
+!2 = metadata !{metadata !"any pointer", metadata !3, i64 0}
+!3 = metadata !{metadata !"omnipotent char", metadata !4, i64 0}
+!4 = metadata !{metadata !"Simple C/C++ TBAA"}
+!5 = metadata !{metadata !6, metadata !6, i64 0}
+!6 = metadata !{metadata !"int", metadata !3, i64 0}