[PATCH] x86: Add ix86_ifunc_ref_local_ok

H.J. Lu hjl.tools@gmail.com
Thu Jul 21 18:53:06 GMT 2022


We can't always use the PLT entry as the function address for local IFUNC
functions.  When the PIC register is needed for PLT call, indirect call
via the PLT entry will fail since the PIC register may not be set up
properly for indirect call.  Add ix86_ifunc_ref_local_ok to return false
when the PLT entry can't be used as local IFUNC function pointers.

gcc/

	PR target/83782
	* config/i386/i386.cc (ix86_ifunc_ref_local_ok): New.
	(TARGET_IFUNC_REF_LOCAL_OK): Use it.

gcc/testsuite/

	PR target/83782
	* gcc.target/i386/pr83782-1.c: Require non-ia32.
	* gcc.target/i386/pr83782-2.c: Likewise.
	* gcc.target/i386/pr83782-3.c: New test.
---
 gcc/config/i386/i386.cc                   | 15 ++++++++++-
 gcc/testsuite/gcc.target/i386/pr83782-1.c |  8 +++---
 gcc/testsuite/gcc.target/i386/pr83782-2.c |  4 +--
 gcc/testsuite/gcc.target/i386/pr83782-3.c | 32 +++++++++++++++++++++++
 4 files changed, 50 insertions(+), 9 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr83782-3.c

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index e03f86d4a23..5e30dc884bf 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -16070,6 +16070,19 @@ ix86_call_use_plt_p (rtx call_op)
   return true;
 }
 
+/* Implement TARGET_IFUNC_REF_LOCAL_OK.  If this hook returns true,
+   the PLT entry will be used as the function address for local IFUNC
+   functions.  When the PIC register is needed for PLT call, indirect
+   call via the PLT entry will fail since the PIC register may not be
+   set up properly for indirect call.  In this case, we should return
+   false.  */
+
+static bool
+ix86_ifunc_ref_local_ok (void)
+{
+  return !flag_pic || (TARGET_64BIT && ix86_cmodel != CM_LARGE_PIC);
+}
+
 /* Return true if the function being called was marked with attribute
    "noplt" or using -fno-plt and we are compiling for non-PIC.  We need
    to handle the non-PIC case in the backend because there is no easy
@@ -24953,7 +24966,7 @@ ix86_libgcc_floating_mode_supported_p
   ix86_get_multilib_abi_name
 
 #undef TARGET_IFUNC_REF_LOCAL_OK
-#define TARGET_IFUNC_REF_LOCAL_OK hook_bool_void_true
+#define TARGET_IFUNC_REF_LOCAL_OK ix86_ifunc_ref_local_ok
 
 #if !TARGET_MACHO && !TARGET_DLLIMPORT_DECL_ATTRIBUTES
 # undef TARGET_ASM_RELOC_RW_MASK
diff --git a/gcc/testsuite/gcc.target/i386/pr83782-1.c b/gcc/testsuite/gcc.target/i386/pr83782-1.c
index ce97b12e65d..85674346aec 100644
--- a/gcc/testsuite/gcc.target/i386/pr83782-1.c
+++ b/gcc/testsuite/gcc.target/i386/pr83782-1.c
@@ -1,4 +1,4 @@
-/* { dg-do compile } */
+/* { dg-do compile { target { ! ia32 } } } */
 /* { dg-require-ifunc "" } */
 /* { dg-options "-O2 -fpic" } */
 
@@ -20,7 +20,5 @@ bar(void)
   return foo;
 }
 
-/* { dg-final { scan-assembler {leal[ \t]foo@GOTOFF\(%[^,]*\),[ \t]%eax} { target ia32 } } } */
-/* { dg-final { scan-assembler {lea(?:l|q)[ \t]foo\(%rip\),[ \t]%(?:e|r)ax} { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler-not "foo@GOT\\\(" { target ia32 } } } */
-/* { dg-final { scan-assembler-not "foo@GOTPCREL\\\(" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler {lea(?:l|q)[ \t]foo\(%rip\),[ \t]%(?:e|r)ax} } } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL\\\(" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr83782-2.c b/gcc/testsuite/gcc.target/i386/pr83782-2.c
index e25d258bbda..a654ded771f 100644
--- a/gcc/testsuite/gcc.target/i386/pr83782-2.c
+++ b/gcc/testsuite/gcc.target/i386/pr83782-2.c
@@ -1,4 +1,4 @@
-/* { dg-do compile } */
+/* { dg-do compile { target { ! ia32 } } } */
 /* { dg-require-ifunc "" } */
 /* { dg-options "-O2 -fpic" } */
 
@@ -20,7 +20,5 @@ bar(void)
   return foo;
 }
 
-/* { dg-final { scan-assembler {leal[ \t]foo@GOTOFF\(%[^,]*\),[ \t]%eax} { target ia32 } } } */
 /* { dg-final { scan-assembler {lea(?:l|q)[ \t]foo\(%rip\),[ \t]%(?:e|r)ax} { target { ! ia32 } } } } */
-/* { dg-final { scan-assembler-not "foo@GOT\\\(" { target ia32 } } } */
 /* { dg-final { scan-assembler-not "foo@GOTPCREL\\\(" { target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr83782-3.c b/gcc/testsuite/gcc.target/i386/pr83782-3.c
new file mode 100644
index 00000000000..1536481cb79
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr83782-3.c
@@ -0,0 +1,32 @@
+/* { dg-do run }  */
+/* { dg-require-ifunc "" } */
+/* { dg-require-effective-target pie } */
+/* { dg-options "-fpie -pie" } */
+
+#include <stdio.h>
+
+static int __attribute__((noinline))
+implementation (void)
+{
+  printf ("'ere I am JH\n");
+  return 0;
+}
+
+static __typeof__ (implementation) *resolver (void)
+{
+  return (void *)implementation;
+}
+
+extern int magic (void) __attribute__ ((ifunc ("resolver")));
+
+__attribute__ ((weak))
+int
+call_magic (int (*ptr) (void))
+{
+  return ptr ();
+}
+
+int main ()
+{
+  return call_magic (magic);
+}
-- 
2.36.1



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