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llvm-mirror/test/CodeGen/X86/ptrtoint-narrow.ll
Shoaib Meenai 29c0224609 [AsmPrinter] Treat a narrowing PtrToInt like Trunc
When printing assembly for PtrToInt, AsmPrinter::lowerConstant
incorrectly assumed that if PtrToInt was not converting to an
int with exactly the same number of bits, it must be widening
to a larger int. But this isn't necessarily true; PtrToInt can
also shrink the size, which is useful when you want to produce
a known 32-bit pointer on a 64-bit platform (on x86_64 ELF
this yields a R_X86_64_32 relocation).

The old behavior of falling through to the widening case for a
narrowing PtrToInt yields bogus assembly code like this, which
fails to assemble because the no-op bit and it accidentally
creates is not a valid relocation:

```
        .long   a&-1
```

The fix is to treat a narrowing PtrToInt exactly the same as
it already treats Trunc: just emit the expression and let
the assembler deal with truncating it in the appropriate way.

Patch by Mat Hostetter <mjh@fb.com>.

Differential Revision: https://reviews.llvm.org/D61325

llvm-svn: 361508
2019-05-23 16:29:09 +00:00

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LLVM

; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
@ptr = external global i8, align 1
@ref = constant i32 ptrtoint (i8* @ptr to i32), align 4
; CHECK: .long ptr{{$}}