Bobby Bruce has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/56243 )
Change subject: arch-riscv: rvc instruction is mistaken as branch
......................................................................
arch-riscv: rvc instruction is mistaken as branch
Fetch in O3CPU mistakes the normal non-branching compressed
instructions, and regards it as a branch. This issue interrupts
the consecutive instruction stream, thus affecting performance
of cpu front-end.
This fix sets the compressed for PCState during decoding.
Jira Issue: https://gem5.atlassian.net/browse/GEM5-1137
Change-Id: I7607d563bba8a08869e104877fc3c11c94cbe904
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54644
Reviewed-by: Jin Cui <cuijinb...@gmail.com>
Reviewed-by: Ayaz Akram <yazak...@ucdavis.edu>
Maintainer: Jason Lowe-Power <power...@gmail.com>
Tested-by: kokoro <noreply+kok...@google.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/56243
Reviewed-by: Jason Lowe-Power <power...@gmail.com>
---
M src/arch/riscv/decoder.cc
1 file changed, 26 insertions(+), 0 deletions(-)
Approvals:
Jason Lowe-Power: Looks good to me, approved; Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/arch/riscv/decoder.cc b/src/arch/riscv/decoder.cc
index 4fbcc64..a02415f 100644
--- a/src/arch/riscv/decoder.cc
+++ b/src/arch/riscv/decoder.cc
@@ -105,8 +105,10 @@
if (compressed(emi)) {
next_pc.npc(next_pc.instAddr() + sizeof(machInst) / 2);
+ next_pc.compressed(true);
} else {
next_pc.npc(next_pc.instAddr() + sizeof(machInst));
+ next_pc.compressed(false);
}
return decode(emi, next_pc.instAddr());
--
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Gerrit-Project: public/gem5
Gerrit-Branch: minor-release-v21-2-1
Gerrit-Change-Id: I7607d563bba8a08869e104877fc3c11c94cbe904
Gerrit-Change-Number: 56243
Gerrit-PatchSet: 2
Gerrit-Owner: Bobby Bruce <bbr...@ucdavis.edu>
Gerrit-Reviewer: Ayaz Akram <yazak...@ucdavis.edu>
Gerrit-Reviewer: Bobby Bruce <bbr...@ucdavis.edu>
Gerrit-Reviewer: Jason Lowe-Power <power...@gmail.com>
Gerrit-Reviewer: Jin Cui <cuijinb...@gmail.com>
Gerrit-Reviewer: kokoro <noreply+kok...@google.com>
Gerrit-MessageType: merged
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