From 6475d9434ff3e981160f85d3f1aa07c9e0ace6f2 Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Sun, 6 Feb 2011 20:11:56 +0000
Subject: [PATCH] When loading from a constant, fold inttoptr if the integer
 type and the resulting pointer type both have the same size.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124987 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/ConstantFolding.cpp   | 11 +++++++++++
 test/Transforms/ConstProp/loads.ll | 17 +++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 243611053c2..6c99ad32bbe 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -340,6 +340,17 @@ static bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset,
     return true;
   }
   
+  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
+    if (CE->getOpcode() == Instruction::IntToPtr) {
+      uint64_t PtrSize = TD.getTypeAllocSize(C->getType());
+      uint64_t IntSize = TD.getTypeAllocSize(C->getOperand(0)->getType());
+
+      if (PtrSize == IntSize)
+        return ReadDataFromGlobal(CE->getOperand(0), ByteOffset, CurPtr, 
+                                  BytesLeft, TD);
+    }
+  }
+
   // Otherwise, unknown initializer type.
   return false;
 }
diff --git a/test/Transforms/ConstProp/loads.ll b/test/Transforms/ConstProp/loads.ll
index 9fbba2b3552..74d80aa1872 100644
--- a/test/Transforms/ConstProp/loads.ll
+++ b/test/Transforms/ConstProp/loads.ll
@@ -120,3 +120,20 @@ define i1 @test13() {
 ; CHECK: @test13
 ; CHECK: ret i1 false
 }
+
+@g6 = constant [2 x i8*] [i8* inttoptr (i64 1 to i8*), i8* inttoptr (i64 2 to i8*)]
+define i64 @test14() nounwind {
+entry:
+  %tmp = load i64* bitcast ([2 x i8*]* @g6 to i64*)
+  ret i64 %tmp
+; CHECK: @test14
+; CHECK: ret i64 1
+}
+
+define i64 @test15() nounwind {
+entry:
+  %tmp = load i64* bitcast (i8** getelementptr inbounds ([2 x i8*]* @g6, i32 0, i64 1) to i64*)
+  ret i64 %tmp
+; CHECK: @test15
+; CHECK: ret i64 2
+}
-- 
2.34.1