From af064aeee607b8a69ce5b9d50482431b753b16e1 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Wed, 9 Dec 2009 18:21:46 +0000
Subject: [PATCH] fix hte last remaining known (by me) phi translation bug. 
 When we reanalyze clobbers to forward pieces of large stores to small loads,
 we need to consider the properly phi translated pointer in the store block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90978 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/GVN.cpp | 15 +++++++++------
 test/Transforms/GVN/rle.ll    | 20 ++++++++++++++++----
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index ed4e0d61488..783da6a5635 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -1384,15 +1384,19 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
     MemDepResult DepInfo = Deps[i].getResult();
 
     if (DepInfo.isClobber()) {
+      // The address being loaded in this non-local block may not be the same as
+      // the pointer operand of the load if PHI translation occurs.  Make sure
+      // to consider the right address.
+      Value *Address = Deps[i].getAddress();
+      
       // If the dependence is to a store that writes to a superset of the bits
       // read by the load, we can extract the bits we need for the load from the
       // stored value.
       if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInfo.getInst())) {
         if (TD == 0)
           TD = getAnalysisIfAvailable<TargetData>();
-        if (TD) {
-          int Offset = AnalyzeLoadFromClobberingStore(LI->getType(),
-                                                      LI->getPointerOperand(),
+        if (TD && Address) {
+          int Offset = AnalyzeLoadFromClobberingStore(LI->getType(), Address,
                                                       DepSI, *TD);
           if (Offset != -1) {
             ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
@@ -1408,9 +1412,8 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
       if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(DepInfo.getInst())) {
         if (TD == 0)
           TD = getAnalysisIfAvailable<TargetData>();
-        if (TD) {
-          int Offset = AnalyzeLoadFromClobberingMemInst(LI->getType(),
-                                                        LI->getPointerOperand(),
+        if (TD && Address) {
+          int Offset = AnalyzeLoadFromClobberingMemInst(LI->getType(), Address,
                                                         DepMI, *TD);
           if (Offset != -1) {
             ValuesPerBlock.push_back(AvailableValueInBlock::getMI(DepBB, DepMI,
diff --git a/test/Transforms/GVN/rle.ll b/test/Transforms/GVN/rle.ll
index 46fc818daa3..d419fd24240 100644
--- a/test/Transforms/GVN/rle.ll
+++ b/test/Transforms/GVN/rle.ll
@@ -469,6 +469,9 @@ exit:
 define i8 @phi_trans4(i8* %p) {
 ; CHECK: @phi_trans4
 entry:
+  %X3 = getelementptr i8* %p, i32 192
+  store i8 192, i8* %X3
+  
   %X = getelementptr i8* %p, i32 4
   %Y = load i8* %X
   br label %loop
@@ -476,11 +479,15 @@ entry:
 loop:
   %i = phi i32 [4, %entry], [192, %loop]
   %X2 = getelementptr i8* %p, i32 %i
-  %Y2 = load i8* %X
+  %Y2 = load i8* %X2
+  
+; CHECK: loop:
+; CHECK-NEXT: %Y2 = phi i8 [ %Y, %entry ], [ 0, %loop ]
+; CHECK-NOT: load i8
   
   %cond = call i1 @cond2()
 
-  %Z = bitcast i8 *%X2 to i32*
+  %Z = bitcast i8 *%X3 to i32*
   store i32 0, i32* %Z
   br i1 %cond, label %loop, label %out
   
@@ -492,6 +499,7 @@ out:
 define i8 @phi_trans5(i8* %p) {
 ; CHECK: @phi_trans5
 entry:
+  
   %X4 = getelementptr i8* %p, i32 2
   store i8 19, i8* %X4
   
@@ -502,8 +510,7 @@ entry:
 loop:
   %i = phi i32 [4, %entry], [3, %cont]
   %X2 = getelementptr i8* %p, i32 %i
-  %Y2 = load i8* %X2
-  ;; FIXME: This load is being incorrectly replaced!
+  %Y2 = load i8* %X2  ; Ensure this load is not being incorrectly replaced.
   %cond = call i1 @cond2()
   br i1 %cond, label %cont, label %out
 
@@ -511,6 +518,11 @@ cont:
   %Z = getelementptr i8* %X2, i32 -1
   %Z2 = bitcast i8 *%Z to i32*
   store i32 50462976, i32* %Z2  ;; (1 << 8) | (2 << 16) | (3 << 24)
+
+
+; CHECK: store i32
+; CHECK-NEXT: getelementptr i8* %p, i32 3
+; CHECK-NEXT: load i8*
   br label %loop
   
 out: