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!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13834 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 6d39c50e3fbd9c18f1d64add4552815db9fa2871..532747b0336ceccbaed447abc11e843751cbb496 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/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;
 }