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Differential D68548

[Mips] Fix evaluating J-format branch targets
ClosedPublic

Authored by jrtc27 on Oct 5 2019, 5:30 PM.

Details

Reviewers
atanasyan
Commits
rG19ede2f53b78: [Mips] Fix evaluating J-format branch targets
rL373906: [Mips] Fix evaluating J-format branch targets
Summary

J/JAL/JALX/JALS are absolute branches, but stay within the current
256 MB-aligned region, so we must include the high bits of the
instruction address when calculating the branch target.

Diff Detail

Event Timeline

jrtc27 created this revision.Oct 5 2019, 5:30 PM
Herald added a project: Restricted Project. · View Herald TranscriptOct 5 2019, 5:30 PM
Herald added subscribers: llvm-commits, hiraditya, arichardson, sdardis. · View Herald Transcript
Harbormaster completed remote builds in B39051: Diff 223400.Oct 5 2019, 5:30 PM
jrtc27 updated this revision to Diff 223401.Oct 5 2019, 5:35 PM

Removed unwanted changes

Harbormaster completed remote builds in B39052: Diff 223401.Oct 5 2019, 5:35 PM
atanasyan accepted this revision.Oct 7 2019, 6:57 AM

LGTM. Thanks for the patch.

This revision is now accepted and ready to land.Oct 7 2019, 6:57 AM
Closed by commit rL373906: [Mips] Fix evaluating J-format branch targets (authored by atanasyan). · Explain WhyOct 7 2019, 10:14 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents

PathSize
llvm/
lib/
Target/
Mips/
MCTargetDesc/
11 lines
test/
MC/
Mips/
17 lines
17 lines

Diff 223401

llvm/lib/Target/Mips/MCTargetDesc/MipsMCTargetDesc.cpp

Show First 20 Lines • Show All 137 Lines • ▼ Show 20 Linespublic:
bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size, bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
uint64_t &Target) const override { uint64_t &Target) const override {
unsigned NumOps = Inst.getNumOperands(); unsigned NumOps = Inst.getNumOperands();
if (NumOps == 0) if (NumOps == 0)
return false; return false;
switch (Info->get(Inst.getOpcode()).OpInfo[NumOps - 1].OperandType) { switch (Info->get(Inst.getOpcode()).OpInfo[NumOps - 1].OperandType) {
case MCOI::OPERAND_UNKNOWN: case MCOI::OPERAND_UNKNOWN:
case MCOI::OPERAND_IMMEDIATE: case MCOI::OPERAND_IMMEDIATE: {
// jal, bal ... // j, jal, jalx, jals
Target = Inst.getOperand(NumOps - 1).getImm(); // Absolute branch within the current 256 MB-aligned region
uint64_t Region = Addr & ~uint64_t(0xfffffff);
Target = Region + Inst.getOperand(NumOps - 1).getImm();
return true; return true;
}
case MCOI::OPERAND_PCREL: case MCOI::OPERAND_PCREL:
// b, j, beq ... // b, beq ...
Target = Addr + Inst.getOperand(NumOps - 1).getImm(); Target = Addr + Inst.getOperand(NumOps - 1).getImm();
return true; return true;
default: default:
return false; return false;
} }
} }
}; };
} }
▲ Show 20 Lines • Show All 49 Lines • Show Last 20 Lines

llvm/test/MC/Mips/micromips-jump-pc-region.s

  • This file was added.
# RUN: llvm-mc -triple=mips -mcpu=mips32 -mattr=+micromips -filetype=obj < %s \
#!RUN: | llvm-objdump -d - | FileCheck %s
.set noreorder
# Force us into the second 256 MB region with a non-zero instruction index
.org 256*1024*1024 + 12
# CHECK-LABEL: 1000000c foo:
# CHECK-NEXT: 1000000c: d4 00 00 06 j 12 <foo>
# CHECK-NEXT: 10000010: f4 00 00 08 jal 16 <foo+0x4>
# CHECK-NEXT: 10000014: f0 00 00 05 jalx 20 <foo+0x8>
# CHECK-NEXT: 10000018: 74 00 00 0c jals 24 <foo+0xc>
foo:
j 12
jal 16
jalx 20
jals 24

llvm/test/MC/Mips/mips-jump-pc-region.s

  • This file was added.
# RUN: llvm-mc -triple=mips -mcpu=mips32 -filetype=obj < %s \
#!RUN: | llvm-objdump -d - | FileCheck %s
# RUN: llvm-mc -triple=mips64 -mcpu=mips64 -filetype=obj < %s \
#!RUN: | llvm-objdump -d - | FileCheck %s
.set noreorder
# Force us into the second 256 MB region with a non-zero instruction index
.org 256*1024*1024 + 12
# CHECK-LABEL: 1000000c foo:
# CHECK-NEXT: 1000000c: 08 00 00 03 j 12 <foo>
# CHECK-NEXT: 10000010: 0c 00 00 04 jal 16 <foo+0x4>
# CHECK-NEXT: 10000014: 74 00 00 05 jalx 20 <foo+0x8>
foo:
j 12
jal 16
jalx 20