binutils-gdb/ld/testsuite/ld-arm/fix-arm1176-on.d
Tamar Christina b4e87f2c1e Arm: Fix performance issue with thumb-2 tailcalls
We currently use a padding NOP after a Thumb to Arm interworking veneer (BX pc).
The NOP is never executed but may result in a performance penalty on some cores.

For this reason this patch changes the NOPs after Thumb to Arm veneers into B .-2
and adds a note to this in the source code for future reference.

bfd/ChangeLog:

	* elf32-arm.c (elf32_thumb2_plt_entry, elf32_arm_plt_thumb_stub,
	elf32_arm_stub_long_branch_v4t_thumb_thumb,
	elf32_arm_stub_long_branch_v4t_thumb_arm,
	elf32_arm_stub_short_branch_v4t_thumb_arm,
	elf32_arm_stub_long_branch_v4t_thumb_arm_pic,
	elf32_arm_stub_long_branch_v4t_thumb_thumb_pic,
	elf32_arm_stub_long_branch_v4t_thumb_tls_pic): Change nop to branch to
	previous instruction.

ld/ChangeLog:

	* testsuite/ld-arm/cortex-a8-fix-b-plt.d: Update Testcase.
	* testsuite/ld-arm/cortex-a8-fix-b-rel-arm.d: Likewise.
	* testsuite/ld-arm/cortex-a8-fix-bcc-plt.d: Likewise.
	* testsuite/ld-arm/farcall-cond-thumb-arm.d: Likewise.
	* testsuite/ld-arm/farcall-mixed-app.d: Likewise.
	* testsuite/ld-arm/farcall-mixed-app2.d: Likewise.
	* testsuite/ld-arm/farcall-mixed-lib-v4t.d: Likewise.
	* testsuite/ld-arm/farcall-thumb-arm-pic-veneer.d: Likewise.
	* testsuite/ld-arm/farcall-thumb-arm-short.d: Likewise.
	* testsuite/ld-arm/farcall-thumb-arm.d: Likewise.
	* testsuite/ld-arm/farcall-thumb-thumb-pic-veneer.d: Likewise.
	* testsuite/ld-arm/farcall-thumb-thumb.d: Likewise.
	* testsuite/ld-arm/fix-arm1176-on.d: Likewise.
	* testsuite/ld-arm/ifunc-10.dd: Likewise.
	* testsuite/ld-arm/ifunc-2.dd: Likewise.
	* testsuite/ld-arm/ifunc-4.dd: Likewise.
	* testsuite/ld-arm/ifunc-6.dd: Likewise.
	* testsuite/ld-arm/ifunc-8.dd: Likewise.
	* testsuite/ld-arm/jump-reloc-veneers-long.d: Likewise.
	* testsuite/ld-arm/mixed-app.d: Likewise.
	* testsuite/ld-arm/thumb2-b-interwork.d: Likewise.
	* testsuite/ld-arm/tls-longplt.d: Likewise.
	* testsuite/ld-arm/tls-thumb1.d: Likewise.
2019-08-20 16:35:28 +01:00

21 lines
527 B
Makefile

.+: file format elf32-(big|little)arm.*
Disassembly of section .foo:
[0-9a-f]+ <_start>:
+[0-9a-f]+: f000 f800 bl 2001018 <__func_to_branch_to_veneer>
[0-9a-f]+ <__func_to_branch_to_veneer>:
+[0-9a-f]+: 4778 bx pc
+[0-9a-f]+: e7fd b.n .+ <.+>
+[0-9a-f]+: e51ff004 ldr pc, \[pc, #-4\] ; 2001020 <__func_to_branch_to_veneer\+0x8>
+[0-9a-f]+: ........ .word 0x........
+[0-9a-f]+: 00000000 .word 0x00000000
Disassembly of section .text:
[0-9a-f]+ <func_to_branch_to>:
+[0-9a-f]+: e12fff1e bx lr