[AArch64] Bad machine code: Using a killed virtual register

[sjoerdmeijer]

A build with expensive checks enabled, and this input:

https://godbolt.org/z/rdYfM1obh / https://godbolt.org/z/vse3EGahG

#include <algorithm>
int a;
void c(bool b[][9]) {
  for (long d((char)62021 - 7); d; d += 2ULL)
    a -= std::max(b[d][d], b[1][1]);
}

runs in to this error when compiled with clang++ -Ofast -mcpu=grace test.cpp:

*** Bad machine code: Using a killed virtual register ***
- function:    _Z1cPA9_b
- basic block: %bb.1 vector.body (0xaaaab373d9d0)
- instruction: %41:gpr64all = COPY %82:gpr64sp
- operand 1:   %82:gpr64sp
fatal error: error in backend: Found 1 machine code errors.

[llvmbot]

@llvm/issue-subscribers-backend-aarch64

Author: Sjoerd Meijer (sjoerdmeijer)

A build with expensive checks enabled, and this input:

#include <algorithm>
int a;
void c(bool b[][9]) {
  for (long d((char)62021 - 7); d; d += 2ULL)
    a -= std::max(b[d][d], b[1][1]);
}

runs in to this error when compiled with clang++ -Ofast -mcpu=grace test.cpp:

*** Bad machine code: Using a killed virtual register ***
- function:    _Z1cPA9_b
- basic block: %bb.1 vector.body (0xaaaab373d9d0)
- instruction: %41:gpr64all = COPY %82:gpr64sp
- operand 1:   %82:gpr64sp
fatal error: error in backend: Found 1 machine code errors.

[sjoerdmeijer]

CC: @davemgreen , @david-arm , @paulwalker-arm , @sdesmalen-arm

[davemgreen]

@jcohen-apple Could this be triggering #142941?

[jcohen-apple]

Checking

[jcohen-apple]

The above PR fixes the issue, waiting for review.