enhance FoldReinterpretLoadFromConstPtr to handle loads of up to 32

bytes (i256).

llvm-svn: 84941

2 files changed, 19 insertions, 6 deletions

diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 3294865a10a..30305049614 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -232,7 +232,7 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
   }
   
   unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
-  if (BytesLoaded > 8 || BytesLoaded == 0) return 0;
+  if (BytesLoaded > 32 || BytesLoaded == 0) return 0;
   
   GlobalValue *GVal;
   int64_t Offset;
@@ -253,16 +253,18 @@ static Constant *FoldReinterpretLoadFromConstPtr(Constant *C,
   if (uint64_t(Offset) >= TD.getTypeAllocSize(GV->getInitializer()->getType()))
     return UndefValue::get(IntType);
   
-  unsigned char RawBytes[8] = {0};
+  unsigned char RawBytes[32] = {0};
   if (!ReadDataFromGlobal(GV->getInitializer(), Offset, RawBytes,
                           BytesLoaded, TD))
     return 0;
 
-  uint64_t ResultVal = 0;
-  for (unsigned i = 0; i != BytesLoaded; ++i)
-    ResultVal |= (uint64_t)RawBytes[i] << (i * 8);
+  APInt ResultVal(IntType->getBitWidth(), 0);
+  for (unsigned i = 0; i != BytesLoaded; ++i) {
+    ResultVal <<= 8;
+    ResultVal |= APInt(IntType->getBitWidth(), RawBytes[BytesLoaded-1-i]);
+  }
 
-  return ConstantInt::get(IntType, ResultVal);
+  return ConstantInt::get(IntType->getContext(), ResultVal);
 }
 
 /// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
diff --git a/llvm/test/Transforms/ConstProp/loads.ll b/llvm/test/Transforms/ConstProp/loads.ll
index f3633cc4438..3096ed347cb 100644
--- a/llvm/test/Transforms/ConstProp/loads.ll
+++ b/llvm/test/Transforms/ConstProp/loads.ll
@@ -4,6 +4,7 @@ target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f3
 
 @test1 = constant {{i32,i8},i32} {{i32,i8} { i32 -559038737, i8 186 }, i32 -889275714 }
 @test2 = constant double 1.0
+@test3 = constant {i64, i64} { i64 123, i64 112312312 }
 
 ; Simple load
 define i32 @test1() {
@@ -66,3 +67,13 @@ define double @test8() {
 ; @test8
 ; CHECK: ret double 0xDEADBEBA
 }
+
+
+; i128 load.
+define i128 @test9() {
+  %r = load i128* bitcast({i64, i64}* @test3 to i128*)
+  ret i128 %r
+
+; @test9
+; CHECK: ret i128 112312312
+}