On Wed, Jul 1, 2026 at 6:07 AM H.J. Lu <[email protected]> wrote: > > Revert changes in ix86_find_max_used_stack_alignment > > 7b39d7b3b84 Correct x86: Call ix86_access_stack_p only for larger alignment > c8a84242e4b Update x86: Call ix86_access_stack_p only for larger alignment > f511bf93f94 x86: Call ix86_access_stack_p only for larger alignment > a7cce1afee8 x86: Call ix86_access_stack_p only with symbolic constant load > b54533a2863 x86: Update stack alignment only if stack is used > b9ea3b2ef98 x86: Properly find the maximum stack slot alignment > > Rewrite ix86_find_max_used_stack_alignment based on RTL points-to info > with find_base_term and static_reg_base_value. If RTL points-to info > isn't available, > > 1. Use ix86_decompose_address to check for symbolic displacement. > 2. Check MEM_EXPR for incoming parameter reference and non-local reference. > > Update the maximum stack slot alignment from memory alignment only if its > base may point to stack or frame pointers. > > Tested on Linux/x86-64. The compile times of PR target/124165 and PR > target/124684 test are unchanged. > > PR target/109780 > PR target/109093 > PR target/123210 > PR target/124098 > PR target/124165 > PR target/124684 > PR target/124759 > PR target/124789 > * alias.cc (static_reg_base_value): Moved to rtl.h. > (find_base_term): Remove static. > * alias.h (find_base_term): New prototype. > * function.cc (thread_prologue_and_epilogue_insns): Call > init_alias_analysis and end_alias_analysis. > * rtl.h (static_reg_base_value): Moved from alias.cc. > * config/i386/i386.cc (stack_access_data): Removed. > (ix86_find_all_reg_uses_1): Likewise. > (ix86_find_all_reg_uses): Likewise. > (ix86_access_stack_p): Likewise. > (ix86_need_alignment_p_2): Likewise. > (ix86_need_alignment_p_1): Likewise. > (ix86_need_alignment_p): Likewise. > (ix86_update_stack_alignment_2): New function. > (ix86_update_stack_alignment_1): Likewise. > (ix86_update_stack_alignment): Rewrite. > (ix86_find_max_used_stack_alignment): If check_stack_slot is > true, call ix86_update_stack_alignment on each INSN. > > Signed-off-by: H.J. Lu <[email protected]> > Co-Authored-By: Richard Biener <[email protected]>
I hope that ix86_update_stack_alignment_2 covers all exceptions, so the patch won't introduce unnecessary stack realignments. OTOH, the patch now heavily builds on generic RTL analysis, so perhaps a middle-end person should look if the usage is correct. The patch also needs separate approval for the changes in generic parts. So, LGTM for the x86 part, but please stay around for possible fallout. Thanks, Uros.
