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[binutils-gdb] RISC-V: Change CALL macro to use ra as the temporary address register
- From: sergiodj+buildbot at sergiodj dot net
- To: gdb-testers at sourceware dot org
- Date: Tue, 02 May 2017 19:01:42 -0400
- Subject: [binutils-gdb] RISC-V: Change CALL macro to use ra as the temporary address register
- Authentication-results: sourceware.org; auth=none
*** TEST RESULTS FOR COMMIT 43e379d74c994fe431368b5f25f778bf601a2981 ***
Author: Michael Clark <michaeljclark@mac.com>
Branch: master
Commit: 43e379d74c994fe431368b5f25f778bf601a2981
RISC-V: Change CALL macro to use ra as the temporary address register
e.g.
1: auipc ra, %pcrel_hi(symbol)
jalr ra, %pcrel_lo(1b)(ra)
The use of ra instead of t1 for address construction provides an
opportunity for a microarchitecture to elide the write of the
destination address, and instead read the target address as an
immediate spread across the fused auipc+jalr pair. The link
register ra in the jalr overwrites the target address temporary.
2017-05-01 Michael Clark <michaeljclark@mac.com>
* riscv-opc.c (riscv_opcodes) <call>: Use RA not T1 as a temporary
register.