Fix InstCombine/load.ll & PR347.

This code hadn't been updated after the "structs with more than 256 elements"
related changes to the GEP instruction.  Also it was not handling the
ConstantAggregateZero class.

Now it does!

llvm-svn: 13834

1 files changed, 24 insertions, 12 deletions

diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index 6d39c50e3fb..532747b0336 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2852,19 +2852,31 @@ static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
 
   // Loop over all of the operands, tracking down which value we are
   // addressing...
-  for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i)
-    if (ConstantUInt *CU = dyn_cast<ConstantUInt>(CE->getOperand(i))) {
-      ConstantStruct *CS = dyn_cast<ConstantStruct>(C);
-      if (CS == 0) return 0;
-      if (CU->getValue() >= CS->getValues().size()) return 0;
-      C = cast<Constant>(CS->getValues()[CU->getValue()]);
-    } else if (ConstantSInt *CS = dyn_cast<ConstantSInt>(CE->getOperand(i))) {
-      ConstantArray *CA = dyn_cast<ConstantArray>(C);
-      if (CA == 0) return 0;
-      if ((uint64_t)CS->getValue() >= CA->getValues().size()) return 0;
-      C = cast<Constant>(CA->getValues()[CS->getValue()]);
-    } else 
+  gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
+  for (++I; I != E; ++I)
+    if (const StructType *STy = dyn_cast<StructType>(*I)) {
+      ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
+      assert(CU->getValue() < STy->getNumElements() &&
+             "Struct index out of range!");
+      if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
+        C = cast<Constant>(CS->getValues()[CU->getValue()]);
+      } else if (isa<ConstantAggregateZero>(C)) {
+	C = Constant::getNullValue(STy->getElementType(CU->getValue()));
+      } else {
+        return 0;
+      }
+    } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
+      const ArrayType *ATy = cast<ArrayType>(*I);
+      if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
+      if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
+        C = cast<Constant>(CA->getValues()[CI->getRawValue()]);
+      else if (isa<ConstantAggregateZero>(C))
+        C = Constant::getNullValue(ATy->getElementType());
+      else
+        return 0;
+    } else {
       return 0;
+    }
   return C;
 }