[all-commits] [llvm/llvm-project] b43235: [DebugInfo] Fix DwarfExpression::addConstantFP for...

[Björn Pettersson via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: b43235a76c231cf15d28f073780e868b71c7bab0
      https://github.com/llvm/llvm-project/commit/b43235a76c231cf15d28f073780e868b71c7bab0
  Author: Bjorn Pettersson <bjorn.a.pettersson at ericsson.com>
  Date:   2020-08-20 (Thu, 20 Aug 2020)

  Changed paths:
    M llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp

  Log Message:
  -----------
  [DebugInfo] Fix DwarfExpression::addConstantFP for float on big-endian

The byte swapping, when dealing with 4 byte (float) FP constants
in DwarfExpression::addConstantFP, added in commit ef8992b9f0189005
was not correct. It always performed byte swapping using an
uint64_t value. When dealing with 4 byte values the 4 interesting
bytes ended up in the big end of the uint64_t, but later we emitted
the 4 bytes at the little end. So we ended up with zeroes being
emitted and faulty debug information.

This patch simplifies things a bit, IMHO. Using the APInt
representation throughout the function, instead of looking at
the internal representation using getRawBytes and without using
reinterpret_cast etc. And using API.byteSwap() should result in
correct byte swapping independent of APInt being 4 or 8 bytes.

Differential Revision: https://reviews.llvm.org/D86272