From 8d057d1f1fe5bf20d32912bc65ad620810583107 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 5 Dec 2023 13:17:57 +0100
Subject: [PATCH] i386: Fix -fcf-protection -Os ICE due to movabsq peephole2
[PR112845]
The following testcase ICEs in the movabsq $(i32 << shift), r64 peephole2
I've added a while back to use smaller code than movabsq if possible.
If i32 is 0xfa1e0ff3 and shift is not divisible by 8, then it creates
an invalid insn (as 0xfa1e0ff3 CONST_INT is not allowed as
x86_64_immediate_operand nor x86_64_zext_immediate_operand), the peephole2
even triggers on it again and again (this time with shift 0) until it gives
up.
The following patch fixes that. As ix86_endbr_immediate_operand needs a
CONST_INT and it is hopefully rare, I chose to use FAIL rather than handling
it in the condition (where I'd probably need to call ctz_hwi again etc.).
2023-12-05 Jakub Jelinek <jakub@redhat.com>
PR target/112845
* config/i386/i386.md (movabsq $(i32 << shift), r64 peephole2): FAIL
if the new immediate is ix86_endbr_immediate_operand.
(cherry picked from commit e0786ca9a18c50ad08c40936b228e325193664b8)
---
gcc/config/i386/i386.md | 5 ++++-
gcc/testsuite/gcc.dg/pr112845.c | 9 +++++++++
2 files changed, 13 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/pr112845.c
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 52ee2c49a624..01c698257bb9 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -2546,7 +2546,10 @@
(clobber (reg:CC FLAGS_REG))])]
{
int shift = ctz_hwi (UINTVAL (operands[1]));
- operands[1] = gen_int_mode (UINTVAL (operands[1]) >> shift, DImode);
+ rtx op1 = gen_int_mode (UINTVAL (operands[1]) >> shift, DImode);
+ if (ix86_endbr_immediate_operand (op1, VOIDmode))
+ FAIL;
+ operands[1] = op1;
operands[2] = gen_int_mode (shift, QImode);
})
diff --git a/gcc/testsuite/gcc.dg/pr112845.c b/gcc/testsuite/gcc.dg/pr112845.c
new file mode 100644
index 000000000000..ece6f451e758
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr112845.c
@@ -0,0 +1,9 @@
+/* PR target/112845 */
+/* { dg-do compile { target cet } } */
+/* { dg-options "-Os -fcf-protection" } */
+
+unsigned long long
+foo (void)
+{
+ return 0xfa1e0ff3ULL << 3;
+}
--
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