[gcc r11-3418] [RS6000] Power10 libffi fixes

[gcc r11-3418] [RS6000] Power10 libffi fixes

[Alan Modra]

https://gcc.gnu.org/g:08cd8d5929eac84b27788d8483fd75ab7ad13129

commit r11-3418-g08cd8d5929eac84b27788d8483fd75ab7ad13129
Author: Alan Modra <amodra@gmail.com>
Date:   Fri Sep 18 23:21:05 2020 +0930

    [RS6000] Power10 libffi fixes
    
    Power10 pc-relative code doesn't use or preserve r2 as a TOC pointer.
    That means calling between pc-relative and TOC using code can't be
    done without intervening linker stubs, and a call from TOC code to
    pc-relative code must have a nop after the bl in order to restore r2.
    
    Now the PowerPC libffi assembly code doesn't use r2 except for the
    implicit use when making calls back to C, ffi_closure_helper_LINUX64
    and ffi_prep_args64.  So changing the assembly to interoperate with
    pc-relative code without stubs is easily done.
    
            * src/powerpc/linux64.S (ffi_call_LINUX64): Don't emit global
            entry when __PCREL__.  Call using @notoc.  Add nops.
            * src/powerpc/linux64_closure.S (ffi_closure_LINUX64): Likewise.
            (ffi_go_closure_linux64): Likewise.

Diff:
---
 libffi/src/powerpc/linux64.S         |  8 ++++++++
 libffi/src/powerpc/linux64_closure.S | 12 +++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/libffi/src/powerpc/linux64.S b/libffi/src/powerpc/linux64.S
index b2ae60ead6e..f0006fe90c5 100644
--- a/libffi/src/powerpc/linux64.S
+++ b/libffi/src/powerpc/linux64.S
@@ -36,8 +36,10 @@
 	.cfi_startproc
 # if _CALL_ELF == 2
 ffi_call_LINUX64:
+#  ifndef __PCREL__
 	addis	%r2, %r12, .TOC.-ffi_call_LINUX64@ha
 	addi	%r2, %r2, .TOC.-ffi_call_LINUX64@l
+#  endif
 	.localentry ffi_call_LINUX64, . - ffi_call_LINUX64
 # else
 	.section	".opd","aw"
@@ -89,9 +91,15 @@ ffi_call_LINUX64:
 	/* Call ffi_prep_args64.  */
 	mr	%r4, %r1
 # if defined _CALL_LINUX || _CALL_ELF == 2
+#  ifdef __PCREL__
+	bl	ffi_prep_args64@notoc
+#  else
 	bl	ffi_prep_args64
+	nop
+#  endif
 # else
 	bl	.ffi_prep_args64
+	nop
 # endif
 
 # if _CALL_ELF == 2
diff --git a/libffi/src/powerpc/linux64_closure.S b/libffi/src/powerpc/linux64_closure.S
index 6487d2a2970..3e30db36190 100644
--- a/libffi/src/powerpc/linux64_closure.S
+++ b/libffi/src/powerpc/linux64_closure.S
@@ -37,8 +37,10 @@
 	.cfi_startproc
 # if _CALL_ELF == 2
 ffi_closure_LINUX64:
+#  ifndef __PCREL__
 	addis	%r2, %r12, .TOC.-ffi_closure_LINUX64@ha
 	addi	%r2, %r2, .TOC.-ffi_closure_LINUX64@l
+#  endif
 	.localentry ffi_closure_LINUX64, . - ffi_closure_LINUX64
 # else
 	.section        ".opd","aw"
@@ -143,7 +145,7 @@ ffi_closure_LINUX64:
 	stfd	%f12, -104+(11*8)(%r1)
 	stfd	%f13, -104+(12*8)(%r1)
 
-	# load up the pointer to the saved fpr registers */
+	# load up the pointer to the saved fpr registers
 	addi	%r8, %r1, -104
 
 	# load up the pointer to the result storage
@@ -155,9 +157,15 @@ ffi_closure_LINUX64:
 
 	# make the call
 # if defined _CALL_LINUX || _CALL_ELF == 2
+#  ifdef __PCREL__
+	bl ffi_closure_helper_LINUX64@notoc
+#  else
 	bl ffi_closure_helper_LINUX64
+	nop
+#  endif
 # else
 	bl .ffi_closure_helper_LINUX64
+	nop
 # endif
 .Lret:
 
@@ -396,8 +404,10 @@ ffi_closure_LINUX64:
 	.cfi_startproc
 # if _CALL_ELF == 2
 ffi_go_closure_linux64:
+#  ifndef __PCREL__
 	addis	%r2, %r12, .TOC.-ffi_go_closure_linux64@ha
 	addi	%r2, %r2, .TOC.-ffi_go_closure_linux64@l
+#  endif
 	.localentry ffi_go_closure_linux64, . - ffi_go_closure_linux64
 # else
 	.section        ".opd","aw"