[gcc/devel/c++-coroutines] i386: Rewrite restore_stack_nonlocal expander [PR96536].
Iain D Sandoe
iains@gcc.gnu.org
Tue Aug 18 18:57:15 GMT 2020
https://gcc.gnu.org/g:f8104bb9dc2365d268ca93e43a24f42e8314fcc1
commit f8104bb9dc2365d268ca93e43a24f42e8314fcc1
Author: Uros Bizjak <ubizjak@gmail.com>
Date: Tue Aug 18 17:31:49 2020 +0200
i386: Rewrite restore_stack_nonlocal expander [PR96536].
-fcf-protection code in restore_stack_nonlocal uses a branch based on
a clobber result. The patch adds missing compare and completely
rewrites the expander to use high-level functions in RTL construction.
2020-08-18 Uroš Bizjak <ubizjak@gmail.com>
gcc/ChangeLog:
PR target/96536
* config/i386/i386.md (restore_stack_nonlocal): Add missing compare
RTX. Rewrite expander to use high-level functions in RTL construction.
Diff:
---
gcc/config/i386/i386.md | 115 ++++++++++++++++++------------------------------
1 file changed, 43 insertions(+), 72 deletions(-)
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 09dcaa36cf1..fb677e17817 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -19112,15 +19112,17 @@
""
{
rtx stack_slot;
- if ((flag_cf_protection & CF_RETURN))
+
+ if (flag_cf_protection & CF_RETURN)
{
- /* Copy shadow stack pointer to the first slot and stack ppointer
- to the second slot. */
+ /* Copy shadow stack pointer to the first slot
+ and stack pointer to the second slot. */
rtx ssp_slot = adjust_address (operands[0], word_mode, 0);
stack_slot = adjust_address (operands[0], Pmode, UNITS_PER_WORD);
- rtx ssp = force_reg (word_mode, const0_rtx);
- emit_insn (gen_rdssp (word_mode, ssp, ssp));
- emit_move_insn (ssp_slot, ssp);
+
+ rtx reg_ssp = force_reg (word_mode, const0_rtx);
+ emit_insn (gen_rdssp (word_mode, reg_ssp, reg_ssp));
+ emit_move_insn (ssp_slot, reg_ssp);
}
else
stack_slot = adjust_address (operands[0], Pmode, 0);
@@ -19134,95 +19136,64 @@
""
{
rtx stack_slot;
- if ((flag_cf_protection & CF_RETURN))
+
+ if (flag_cf_protection & CF_RETURN)
{
- /* Restore shadow stack pointer from the first slot and stack
- pointer from the second slot. */
+ /* Restore shadow stack pointer from the first slot
+ and stack pointer from the second slot. */
rtx ssp_slot = adjust_address (operands[1], word_mode, 0);
stack_slot = adjust_address (operands[1], Pmode, UNITS_PER_WORD);
- rtx flags, jump, noadj_label, inc_label, loop_label;
- rtx reg_adj, reg_ssp, tmp, clob;
-
/* Get the current shadow stack pointer. The code below will check if
SHSTK feature is enabled. If it is not enabled the RDSSP instruction
is a NOP. */
- reg_ssp = force_reg (word_mode, const0_rtx);
+ rtx reg_ssp = force_reg (word_mode, const0_rtx);
emit_insn (gen_rdssp (word_mode, reg_ssp, reg_ssp));
- /* Compare through substraction the saved and the current ssp to decide
- if ssp has to be adjusted. */
- tmp = gen_rtx_SET (reg_ssp, gen_rtx_MINUS (word_mode, reg_ssp,
- ssp_slot));
- clob = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (CCmode, FLAGS_REG));
- tmp = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, tmp, clob));
- emit_insn (tmp);
+ /* Compare through subtraction the saved and the current ssp
+ to decide if ssp has to be adjusted. */
+ reg_ssp = expand_simple_binop (word_mode, MINUS,
+ reg_ssp, ssp_slot,
+ reg_ssp, 1, OPTAB_DIRECT);
/* Compare and jump over adjustment code. */
- noadj_label = gen_label_rtx ();
- flags = gen_rtx_REG (CCZmode, FLAGS_REG);
- tmp = gen_rtx_EQ (VOIDmode, flags, const0_rtx);
- tmp = gen_rtx_IF_THEN_ELSE (VOIDmode, tmp,
- gen_rtx_LABEL_REF (VOIDmode, noadj_label),
- pc_rtx);
- jump = emit_jump_insn (gen_rtx_SET (pc_rtx, tmp));
- JUMP_LABEL (jump) = noadj_label;
-
- /* Compute the numebr of frames to adjust. */
- reg_adj = gen_lowpart (ptr_mode, reg_ssp);
- tmp = gen_rtx_SET (reg_adj,
- gen_rtx_LSHIFTRT (ptr_mode,
- negate_rtx (ptr_mode, reg_adj),
- GEN_INT ((word_mode == SImode)
- ? 2
- : 3)));
- clob = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (CCmode, FLAGS_REG));
- tmp = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, tmp, clob));
- emit_insn (tmp);
+ rtx noadj_label = gen_label_rtx ();
+ emit_cmp_and_jump_insns (reg_ssp, const0_rtx, EQ, NULL_RTX,
+ word_mode, 1, noadj_label);
- /* Check if number of frames <= 255 so no loop is needed. */
- tmp = gen_rtx_COMPARE (CCmode, reg_adj, GEN_INT (255));
- flags = gen_rtx_REG (CCmode, FLAGS_REG);
- emit_insn (gen_rtx_SET (flags, tmp));
+ /* Compute the number of frames to adjust. */
+ rtx reg_adj = gen_lowpart (ptr_mode, reg_ssp);
+ rtx reg_adj_neg = expand_simple_unop (ptr_mode, NEG, reg_adj,
+ NULL_RTX, 1);
- inc_label = gen_label_rtx ();
- tmp = gen_rtx_LEU (VOIDmode, flags, const0_rtx);
- tmp = gen_rtx_IF_THEN_ELSE (VOIDmode, tmp,
- gen_rtx_LABEL_REF (VOIDmode, inc_label),
- pc_rtx);
- jump = emit_jump_insn (gen_rtx_SET (pc_rtx, tmp));
- JUMP_LABEL (jump) = inc_label;
+ reg_adj = expand_simple_binop (ptr_mode, LSHIFTRT, reg_adj_neg,
+ GEN_INT (exact_log2 (UNITS_PER_WORD)),
+ reg_adj, 1, OPTAB_DIRECT);
- rtx reg_255 = gen_reg_rtx (word_mode);
- emit_move_insn (reg_255, GEN_INT (255));
+ /* Check if number of frames <= 255 so no loop is needed. */
+ rtx inc_label = gen_label_rtx ();
+ emit_cmp_and_jump_insns (reg_adj, GEN_INT (255), LEU, NULL_RTX,
+ ptr_mode, 1, inc_label);
/* Adjust the ssp in a loop. */
- loop_label = gen_label_rtx ();
+ rtx loop_label = gen_label_rtx ();
emit_label (loop_label);
LABEL_NUSES (loop_label) = 1;
+ rtx reg_255 = force_reg (word_mode, GEN_INT (255));
emit_insn (gen_incssp (word_mode, reg_255));
- tmp = gen_rtx_SET (reg_adj, gen_rtx_MINUS (ptr_mode,
- reg_adj,
- GEN_INT (255)));
- clob = gen_rtx_CLOBBER (VOIDmode, gen_rtx_REG (CCmode, FLAGS_REG));
- tmp = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, tmp, clob));
- emit_insn (tmp);
-
- tmp = gen_rtx_COMPARE (CCmode, reg_adj, GEN_INT (255));
- flags = gen_rtx_REG (CCmode, FLAGS_REG);
- emit_insn (gen_rtx_SET (flags, tmp));
-
- /* Jump to the loop label. */
- tmp = gen_rtx_GTU (VOIDmode, flags, const0_rtx);
- tmp = gen_rtx_IF_THEN_ELSE (VOIDmode, tmp,
- gen_rtx_LABEL_REF (VOIDmode, loop_label),
- pc_rtx);
- jump = emit_jump_insn (gen_rtx_SET (pc_rtx, tmp));
- JUMP_LABEL (jump) = loop_label;
+
+ reg_adj = expand_simple_binop (ptr_mode, MINUS,
+ reg_adj, GEN_INT (255),
+ reg_adj, 1, OPTAB_DIRECT);
+
+ /* Compare and jump to the loop label. */
+ emit_cmp_and_jump_insns (reg_adj, GEN_INT (255), GTU, NULL_RTX,
+ ptr_mode, 1, loop_label);
emit_label (inc_label);
LABEL_NUSES (inc_label) = 1;
+
emit_insn (gen_incssp (word_mode, reg_ssp));
emit_label (noadj_label);
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