[Qemu-devel] [Bug 944753] Re: ARM: CORTEX M, PRIMASK and FAULTMASK are misplaced, WINDOWS mingw 4.6.1 bug

[Peter Maydell]

That generated code certainly looks fishy, but really you need to report
gcc bugs to the gcc folks, not us.

I see from your quoted fragments of source code that you're using a
version of QEMU which has a bug in its handling of PRIMASK/FAULTMASK
here, incidentally. Commit d3cb6e2b0 (January, not in a QEMU release
yet) fixes bug 913925 -- we were passing the wrong constant values.

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Title:
  ARM: CORTEX M, PRIMASK and FAULTMASK are misplaced, WINDOWS mingw
  4.6.1 bug

Status in QEMU:
  New

Bug description:
  Just want to warn anyone who hacks QEMU cortex M support under MinGW,
  it seems there is a bug in gcc 4.6.1 that compiles this peace of code
  wrong.

  translate.c:

               if (IS_M(env)) {
                  tmp = tcg_const_i32((insn & (1 << 4)) != 0);
                 /* PRIMASK */
                  if (insn & 2) {
                      addr = tcg_const_i32(16);
                      gen_helper_v7m_msr(cpu_env, addr, tmp);
                      tcg_temp_free_i32(addr);
                  }
                  /* FAULTMASK */
                  if (insn & 1) {
                      addr = tcg_const_i32(17);
                      gen_helper_v7m_msr(cpu_env, addr, tmp);
                      tcg_temp_free_i32(addr);
                  }
                  tcg_temp_free_i32(tmp);
                  gen_lookup_tb(s);

  if we just switch conditions order it will compile OK

                if (IS_M(env)) {
                  tmp = tcg_const_i32((insn & (1 << 4)) != 0);
                  /* FAULTMASK */
                  if (insn & 1) {
                      addr = tcg_const_i32(17);
                      gen_helper_v7m_msr(cpu_env, addr, tmp);
                      tcg_temp_free_i32(addr);
                  }
                  /* PRIMASK */
                  if (insn & 2) {
                      addr = tcg_const_i32(16);
                      gen_helper_v7m_msr(cpu_env, addr, tmp);
                      tcg_temp_free_i32(addr);
                  }
                  tcg_temp_free_i32(tmp);
                  gen_lookup_tb(s);

  I have attached gdb disassembly in the attachment for both cases

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