Extended Description

There's a bug in folding loads of static initializers. If there are bytes with
the high bit set, adjacent bytes are getting set to all ones when the compiler
is running on a host with signed char. Here's a patch that fixes it:

Index: SelectionDAGISel.cpp

RCS file: /var/cvs/llvm/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp,v
retrieving revision 1.319
diff -u -r1.319 SelectionDAGISel.cpp
--- SelectionDAGISel.cpp
+++ SelectionDAGISel.cpp
@@ -3179,7 +3179,7 @@
if (TLI.isLittleEndian())
Offset = Offset + MSB - 1;
for (unsigned i = 0; i != MSB; ++i) {

• Val = (Val << 8) | Str[Offset];

• Val = (Val << 8) | (unsigned char) Str[Offset];
  Offset += TLI.isLittleEndian() ? -1 : 1;
  }
  return DAG.getConstant(Val, VT);

And here's a testcase that reproduces the problem.

target datalayout = "e-p:32:32"
target endian = little
target pointersize = 32
target triple = "i686-pc-linux-gnu"
%fmt = constant [4 x sbyte] c"%x\0A\00"
%bytes = constant [4 x sbyte] c"\AA\BB\CC\DD"

implementation

int %main() {
%y = alloca uint
%c = cast uint* %y to sbyte*
%z = getelementptr [4 x sbyte]* %bytes, int 0, int 0
call void %llvm.memcpy.i32( sbyte* %c, sbyte* %z, uint 4, uint 1 )
%r = load uint* %y
%t = cast [4 x sbyte]* %fmt to sbyte*
%tmp = call int (sbyte*, ...)* %printf( sbyte* %t, uint %r )
ret int 0
}

declare void %llvm.memcpy.i32(sbyte*, sbyte*, uint, uint)

declare int %printf(sbyte*, ...)