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

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index ed4e0d614887c6cb3977c747ec41189ee1ee6ebb..783da6a5635bd6aa4dd76ae8c98069f3756e2911 100644 (file)
--- 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 46fc818daa3d60125852025bd89d04b20897d5b4..d419fd24240cc6650985199ed733dc6b939c34d3 100644 (file)
--- 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: