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Don't create TargetGlobalAddress nodes with offsets that don't fit

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in the 32-bit signed offset field of addresses. Even though this
may be intended, some linkers refuse to relocate code where the
relocated address computation overflows.

Also, fix the sign-extension of constant offsets to use the
actual pointer size, rather than the size of the GlobalAddress
node, which may be different, for example on x86-64 where MVT::i32
is used when the address is being fit into the 32-bit displacement
field.

llvm-svn: 57885
This commit is contained in:
Dan Gohman 2008-10-21 03:38:42 +00:00
parent d346dfe881
commit 269246b034
3 changed files with 16 additions and 2 deletions
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2
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -974,7 +974,7 @@ SDValue SelectionDAG::getGlobalAddress(const GlobalValue *GV,
unsigned Opc;
// Truncate (with sign-extension) the offset value to the pointer size.
unsigned BitWidth = VT.getSizeInBits();
unsigned BitWidth = TLI.getPointerTy().getSizeInBits();
if (BitWidth < 64)
Offset = (Offset << (64 - BitWidth) >> (64 - BitWidth));

2
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -4400,7 +4400,7 @@ X86TargetLowering::LowerGlobalAddress(const GlobalValue *GV,
// Create the TargetGlobalAddress node, folding in the constant
// offset if it is legal.
SDValue Result;
if (!IsPic && !ExtraLoadRequired) {
if (!IsPic && !ExtraLoadRequired && isInt32(Offset)) {
Result = DAG.getTargetGlobalAddress(GV, getPointerTy(), Offset);
Offset = 0;
} else

14
llvm/test/CodeGen/X86/x86-64-disp.ll Normal file
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@ -0,0 +1,14 @@
; RUN: llvm-as < %s | llc -march=x86-64 | grep mov | count 2
; Fold an offset into an address even if it's not a 32-bit
; signed integer.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
target triple = "x86_64-unknown-linux-gnu"
@call_used_regs = external global [53 x i8], align 32
define fastcc void @foo() nounwind {
%t = getelementptr [53 x i8]* @call_used_regs, i64 0, i64 4294967295
store i8 1, i8* %t, align 1
ret void
}