Recent commit introduced a conditional branch in eh_return epilogues
that is not compatible with speculation tracking:
commit 426fddcbdad6746fe70e031f707fb07f55dfb405
Author: Szabolcs Nagy <szabolcs.n...@arm.com>
CommitDate: 2023-11-27 15:52:48 +0000
aarch64: Use br instead of ret for eh_return
Refactor the compare zero and jump pattern and use it to fix the issue.
gcc/ChangeLog:
PR target/112987
* config/aarch64/aarch64.cc (aarch64_gen_compare_zero_and_branch): New.
(aarch64_expand_epilogue): Use the new function.
(aarch64_split_compare_and_swap): Likewise.
(aarch64_split_atomic_op): Likewise.
---
v2: factor out aarch64_gen_compare_zero_and_branch
gcc/config/aarch64/aarch64.cc | 75 +++++++++++++++--------------------
1 file changed, 32 insertions(+), 43 deletions(-)
diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 3d6dd98c5c5..d2014ce1527 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -2637,6 +2637,28 @@ aarch64_gen_compare_reg_maybe_ze (RTX_CODE code, rtx x,
rtx y,
return aarch64_gen_compare_reg (code, x, y);
}
+/* Generate conditional branch to LABEL, comparing X to 0 using CODE.
+ Return the jump instruction. */
+
+static rtx
+aarch64_gen_compare_zero_and_branch (rtx_code code, rtx x,
+ rtx_code_label *label)
+{
+ if (aarch64_track_speculation)
+ {
+ /* Emit an explicit compare instruction, so that we can correctly
+ track the condition codes. */
+ rtx cc_reg = aarch64_gen_compare_reg (code, x, const0_rtx);
+ x = gen_rtx_fmt_ee (code, GET_MODE (cc_reg), cc_reg, const0_rtx);
+ }
+ else
+ x = gen_rtx_fmt_ee (code, VOIDmode, x, const0_rtx);
+
+ x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
+ gen_rtx_LABEL_REF (Pmode, label), pc_rtx);
+ return gen_rtx_SET (pc_rtx, x);
+}
+
/* Consider the operation:
OPERANDS[0] = CODE (OPERANDS[1], OPERANDS[2]) + OPERANDS[3]
@@ -9882,11 +9904,10 @@ aarch64_expand_epilogue (rtx_call_insn *sibcall)
to be SP; letting the CFA move during this adjustment
is just as correct as retaining the CFA from the body
of the function. Therefore, do nothing special. */
- rtx label = gen_label_rtx ();
- rtx x = gen_rtx_EQ (VOIDmode, EH_RETURN_TAKEN_RTX, const0_rtx);
- x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
- gen_rtx_LABEL_REF (Pmode, label), pc_rtx);
- rtx jump = emit_jump_insn (gen_rtx_SET (pc_rtx, x));
+ rtx_code_label *label = gen_label_rtx ();
+ rtx x = aarch64_gen_compare_zero_and_branch (EQ, EH_RETURN_TAKEN_RTX,
+ label);
+ rtx jump = emit_jump_insn (x);
JUMP_LABEL (jump) = label;
LABEL_NUSES (label)++;
emit_insn (gen_add2_insn (stack_pointer_rtx,
@@ -24657,19 +24678,8 @@ aarch64_split_compare_and_swap (rtx operands[])
if (!is_weak)
{
- if (aarch64_track_speculation)
- {
- /* Emit an explicit compare instruction, so that we can correctly
- track the condition codes. */
- rtx cc_reg = aarch64_gen_compare_reg (NE, scratch, const0_rtx);
- x = gen_rtx_NE (GET_MODE (cc_reg), cc_reg, const0_rtx);
- }
- else
- x = gen_rtx_NE (VOIDmode, scratch, const0_rtx);
-
- x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
- gen_rtx_LABEL_REF (Pmode, label1), pc_rtx);
- aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
+ x = aarch64_gen_compare_zero_and_branch (NE, scratch, label1);
+ aarch64_emit_unlikely_jump (x);
}
else
aarch64_gen_compare_reg (NE, scratch, const0_rtx);
@@ -24685,18 +24695,8 @@ aarch64_split_compare_and_swap (rtx operands[])
emit_label (label2);
aarch64_emit_store_exclusive (mode, scratch, mem, rval, model_rtx);
- if (aarch64_track_speculation)
- {
- /* Emit an explicit compare instruction, so that we can correctly
- track the condition codes. */
- rtx cc_reg = aarch64_gen_compare_reg (NE, scratch, const0_rtx);
- x = gen_rtx_NE (GET_MODE (cc_reg), cc_reg, const0_rtx);
- }
- else
- x = gen_rtx_NE (VOIDmode, scratch, const0_rtx);
- x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
- gen_rtx_LABEL_REF (Pmode, label1), pc_rtx);
- aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
+ x = aarch64_gen_compare_zero_and_branch (NE, scratch, label1);
+ aarch64_emit_unlikely_jump (x);
label2 = label3;
}
@@ -24780,19 +24780,8 @@ aarch64_split_atomic_op (enum rtx_code code, rtx
old_out, rtx new_out, rtx mem,
aarch64_emit_store_exclusive (mode, cond, mem,
gen_lowpart (mode, new_out), model_rtx);
- if (aarch64_track_speculation)
- {
- /* Emit an explicit compare instruction, so that we can correctly
- track the condition codes. */
- rtx cc_reg = aarch64_gen_compare_reg (NE, cond, const0_rtx);
- x = gen_rtx_NE (GET_MODE (cc_reg), cc_reg, const0_rtx);
- }
- else
- x = gen_rtx_NE (VOIDmode, cond, const0_rtx);
-
- x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
- gen_rtx_LABEL_REF (Pmode, label), pc_rtx);
- aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
+ x = aarch64_gen_compare_zero_and_branch (NE, cond, label);
+ aarch64_emit_unlikely_jump (x);
/* Emit any final barrier needed for a __sync operation. */
if (is_sync)
--
2.25.1
