When CodeGen'ing unoptimized code, there may be unfolded constant expressions

in global initializers. Instead of aborting, attempt to fold them on the
spot. If folding succeeds, emit the folded expression instead.

This fixes PR6255.

llvm-svn: 95583

1 files changed, 11 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 31326911590..5f730e03c6f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -25,6 +25,7 @@
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/DebugInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
@@ -887,15 +888,16 @@ static const MCExpr *LowerConstant(const Constant *CV, AsmPrinter &AP) {
   }
   
   switch (CE->getOpcode()) {
-  case Instruction::ZExt:
-  case Instruction::SExt:
-  case Instruction::FPTrunc:
-  case Instruction::FPExt:
-  case Instruction::UIToFP:
-  case Instruction::SIToFP:
-  case Instruction::FPToUI:
-  case Instruction::FPToSI:
-  default: llvm_unreachable("FIXME: Don't support this constant cast expr");
+  default:
+    // If the code isn't optimized, there may be outstanding folding
+    // opportunities. Attempt to fold the expression using TargetData as a
+    // last resort before giving up.
+    if (Constant *C = ConstantFoldConstantExpression(CE, AP.TM.getTargetData()))
+      return LowerConstant(C, AP);
+#ifndef NDEBUG
+    CE->dump();
+#endif
+    llvm_unreachable("FIXME: Don't support this constant expr");
   case Instruction::GetElementPtr: {
     const TargetData &TD = *AP.TM.getTargetData();
     // Generate a symbolic expression for the byte address