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

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:
+  default:
-  case Instruction::SExt:
+    // If the code isn't optimized, there may be outstanding folding
-  case Instruction::FPTrunc:
+    // opportunities. Attempt to fold the expression using TargetData as a
-  case Instruction::FPExt:
+    // last resort before giving up.
-  case Instruction::UIToFP:
+    if (Constant *C = ConstantFoldConstantExpression(CE, AP.TM.getTargetData()))
-  case Instruction::SIToFP:
+      return LowerConstant(C, AP);
-  case Instruction::FPToUI:
+#ifndef NDEBUG
-  case Instruction::FPToSI:
+    CE->dump();
-  default: llvm_unreachable("FIXME: Don't support this constant cast expr");
+#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

llvm/test/CodeGen/X86/ptrtoint-constexpr.ll

@@ -6,3 +6,9 @@
 ; CHECK: .quad	r&4294967295
 
 @r = global %union.x { i64 ptrtoint (%union.x* @r to i64) }, align 4
+
+; CHECK:	.globl x
+; CHECK: x:
+; CHECK: .quad	3
+
+@x = global i64 mul (i64 3, i64 ptrtoint (i2* getelementptr (i2* null, i64 1) to i64))