> this is a regression present on all active branches: if you compile the > attached Ada testcase with -O2 -gnatp -fno-omit-frame-pointer for 32-bit > Windows, you'll see that the compiler swaps a load based on the stack pointer > with a store based on the frame pointer, thus clobbering a saved argument: > > pushl %ebp > movl %esp, %ebp > pushl %esi > pushl %ebx > pushl %eax <- %eax save > movl $4108, %eax > call ___chkstk_ms > leal 8(%ebp), %esi > subl %eax, %esp > movl 8(%ebp), %ebx > movl %edx, -20(%ebp) > movl %esi, -12(%ebp) <- fp-based store > movl (%esp,%eax), %eax <- sp-based load > ... wrong value in eax... > > The load and the store are swapped because there are not based on the same > register and the offset between them is seen as variable. The proposed fix is > to add a memory blockage, like in other frame-related constructs. > > Tested on x86/Windows and x86-64/Windows, OK for all active branches? > > > 2019-02-06 Eric Botcazou <ebotca...@adacore.com> > > * config/i386/i386.c (ix86_expand_prologue): Generate a memory blockage > after restoring registers saved to allocate the frame on Windows. > > > 2019-02-06 Eric Botcazou <ebotca...@adacore.com> > > * gnat.dg/opt76.adb: New test.
OK everywhere. Thanks, Uros.
