From 618f17702d09795279717827eeb06632d6ef49e4 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Mon, 8 Feb 2010 22:02:38 +0000
Subject: [PATCH] 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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95583 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/AsmPrinter.cpp  | 20 +++++++++++---------
 test/CodeGen/X86/ptrtoint-constexpr.ll |  6 ++++++
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 31326911590..5f730e03c6f 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/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
diff --git a/test/CodeGen/X86/ptrtoint-constexpr.ll b/test/CodeGen/X86/ptrtoint-constexpr.ll
index 7e33e7916c8..dd9790568ab 100644
--- a/test/CodeGen/X86/ptrtoint-constexpr.ll
+++ b/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))
-- 
2.34.1