https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70439
Bug ID: 70439
Summary: Incorrect DRAP check in ix86_expand_epilogue
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
CC: ubizjak at gmail dot com
Target Milestone: ---
Target: x86
ix86_expand_epilogue has
/* eh_return epilogues need %ecx added to the stack pointer. */
if (style == 2)
{
rtx sa = EH_RETURN_STACKADJ_RTX;
rtx_insn *insn;
/* Stack align doesn't work with eh_return. */
gcc_assert (!stack_realign_drap);
/* Neither does regparm nested functions. */
gcc_assert (!ix86_static_chain_on_stack);
EH_RETURN_STACKADJ_RTX is defined to %ecx, which conflicts with DRAP
which also uses %ecx. When stack_realign_drap is true, ix86_get_drap_rtx
emits DRAP register. But ix86_finalize_stack_realign_flags may set
crtl->stack_realign_needed to false later. When we get ix86_expand_epilogue,
stack_realign_drap is false, but DRAP is actually used, which leads to wrong
code.
