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authorGabe Black <gabeblack@google.com>2017-12-19 23:14:34 -0800
committerGabe Black <gabeblack@google.com>2018-01-10 12:19:54 +0000
commit78524bda5606e1b60615f57ebd6bfe5bcdd71afb (patch)
tree346b73741acae374e37328c1c72c5289278749af /src/cpu
parent3fb4d59a9d66d729b292bf804a8b5fdbe6e40d89 (diff)
downloadgem5-78524bda5606e1b60615f57ebd6bfe5bcdd71afb.tar.xz
alpha,arm,mips,power,riscv,sparc,x86,cpu: Get rid of ISA_HAS_DELAY_SLOT.
This constant is, first, a #define, and second only used in one place. In that one place, it appears that the code it guards is no longer necessary in general. It was originally written to avoid refetching a block of data that you're still in, even if you've moved slightly farther in it because you're skipping the next instruction due to an annulled branch delay slot. In reality however, in SPARC, the one ISA I'm aware of which has this sort of branching behavior, the PC state object will correctly determine that no branch is happening in these cases. Code lower down in the loop will then recompute where fetching should continue based on the next PC, automatically skipping the annulled branch slot without misinterpretting the gap as a branch. This change therefore also removes this block of code. Change-Id: I820ebc9df10aeb4fcb69c12f6a784e9ec616743c Reviewed-on: https://gem5-review.googlesource.com/6821 Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Diffstat (limited to 'src/cpu')
-rw-r--r--src/cpu/o3/fetch_impl.hh11
1 files changed, 0 insertions, 11 deletions
diff --git a/src/cpu/o3/fetch_impl.hh b/src/cpu/o3/fetch_impl.hh
index d8793426b..2e8ec67ae 100644
--- a/src/cpu/o3/fetch_impl.hh
+++ b/src/cpu/o3/fetch_impl.hh
@@ -1277,17 +1277,6 @@ DefaultFetch<Impl>::fetch(bool &status_change)
break;
}
- if (ISA_HAS_DELAY_SLOT && pcOffset == 0) {
- // Walk past any annulled delay slot instructions.
- Addr pcAddr = thisPC.instAddr() & BaseCPU::PCMask;
- while (fetchAddr != pcAddr && blkOffset < numInsts) {
- blkOffset++;
- fetchAddr += instSize;
- }
- if (blkOffset >= numInsts)
- break;
- }
-
MachInst inst = TheISA::gtoh(cacheInsts[blkOffset]);
decoder[tid]->moreBytes(thisPC, fetchAddr, inst);