https://gcc.gnu.org/g:c56dc83e82af319d02a19f0703c301523ab1ef25
commit r13-9005-gc56dc83e82af319d02a19f0703c301523ab1ef25
Author: Tejas Belagod <tejas.bela...@arm.com>
Date: Thu Jan 25 16:05:36 2024 +0530
Arm: Fix incorrect tailcall-generation for indirect calls [PR113780]
This patch fixes a bug that causes indirect calls in PAC-enabled functions
to be tailcalled incorrectly when all argument registers R0-R3 are used.
2024-02-07 Tejas Belagod <tejas.bela...@arm.com>
PR target/113780
* config/arm/arm.cc (arm_function_ok_for_sibcall): Don't allow
tailcalls
for indirect calls with 4 or more arguments in pac-enabled
functions.
* lib/target-supports.exp (v8_1m_main_pacbti): Add
__ARM_FEATURE_PAUTH.
* gcc.target/arm/pac-sibcall.c: New.
(cherry picked from commit f436a2ab6ad15968275c9bbf3bd56647e5559e68)
Diff:
---
gcc/config/arm/arm.cc | 11 +++++++----
gcc/testsuite/gcc.target/arm/pac-sibcall.c | 14 ++++++++++++++
gcc/testsuite/lib/target-supports.exp | 2 ++
3 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index c00c6d7c1e6..bf1c6e36dfc 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -7947,10 +7947,13 @@ arm_function_ok_for_sibcall (tree decl, tree exp)
&& DECL_WEAK (decl))
return false;
- /* We cannot do a tailcall for an indirect call by descriptor if all the
- argument registers are used because the only register left to load the
- address is IP and it will already contain the static chain. */
- if (!decl && CALL_EXPR_BY_DESCRIPTOR (exp) && !flag_trampolines)
+ /* We cannot tailcall an indirect call by descriptor if all the
call-clobbered
+ general registers are live (r0-r3 and ip). This can happen when:
+ - IP contains the static chain, or
+ - IP is needed for validating the PAC signature. */
+ if (!decl
+ && ((CALL_EXPR_BY_DESCRIPTOR (exp) && !flag_trampolines)
+ || arm_current_function_pac_enabled_p()))
{
tree fntype = TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (exp)));
CUMULATIVE_ARGS cum;
diff --git a/gcc/testsuite/gcc.target/arm/pac-sibcall.c
b/gcc/testsuite/gcc.target/arm/pac-sibcall.c
new file mode 100644
index 00000000000..e15bd2f478d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pac-sibcall.c
@@ -0,0 +1,14 @@
+/* If all call-clobbered general registers are live (r0-r3, ip), disable
+ indirect tail-call for a PAC-enabled function. */
+
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arch_v8_1m_main_pacbti_ok } */
+/* { dg-add-options arm_arch_v8_1m_main_pacbti } */
+/* { dg-additional-options "-mbranch-protection=pac-ret+leaf -O2" } */
+
+void fail(void (*f)(int, int, int, int))
+{
+ f(1, 2, 3, 4);
+}
+
+/* { dg-final { scan-assembler-not "bx\tip\t@ indirect register sibling call"
} } */
diff --git a/gcc/testsuite/lib/target-supports.exp
b/gcc/testsuite/lib/target-supports.exp
index c81313ea717..be97693e895 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -5057,6 +5057,8 @@ foreach { armfunc armflag armdefs } {
__ARM_ARCH_8M_BASE__
v8m_main "-march=armv8-m.main -mthumb" __ARM_ARCH_8M_MAIN__
v8_1m_main "-march=armv8.1-m.main -mthumb" __ARM_ARCH_8M_MAIN__
+ v8_1m_main_pacbti "-march=armv8.1-m.main+pacbti+fp -mthumb"
+ "__ARM_ARCH_8M_MAIN__ && __ARM_FEATURE_BTI &&
__ARM_FEATURE_PAUTH"
v9a "-march=armv9-a" __ARM_ARCH_9A__ } {
eval [string map [list FUNC $armfunc FLAG $armflag DEFS $armdefs ] {
proc check_effective_target_arm_arch_FUNC_ok { } {
