[llvm] 3382c24 - [RISCV] Fix RISCVInstrInfo::getInstSizeInBytes for atomics pseudos

[Jessica Clarke via llvm-commits]

Author: Jessica Clarke
Date: 2020-07-15T10:50:55+01:00
New Revision: 3382c243baf2c9761db80e498243f4c57fe64de8

URL: https://github.com/llvm/llvm-project/commit/3382c243baf2c9761db80e498243f4c57fe64de8
DIFF: https://github.com/llvm/llvm-project/commit/3382c243baf2c9761db80e498243f4c57fe64de8.diff

LOG: [RISCV] Fix RISCVInstrInfo::getInstSizeInBytes for atomics pseudos

Summary:
Without these, the generic branch relaxation pass will underestimate the
range required for branches spanning these and we can end up with
"fixup value out of range" errors rather than relaxing the branches.
Some of the instructions in the expansion may end up being compressed
but exactly determining that is awkward, and these conservative values
should be safe, if slightly suboptimal in rare cases.

Reviewers: asb, lenary, luismarques, lewis-revill

Reviewed By: asb, luismarques

Subscribers: hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, MaskRay, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, jfb, PkmX, jocewei, psnobl, benna, Jim, s.egerton, pzheng, sameer.abuasal, apazos, evandro, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77443

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
    llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
    llvm/lib/Target/RISCV/RISCVInstrInfo.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp b/llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
index b49c767ff2ca..26ce16486bd9 100644
--- a/llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
+++ b/llvm/lib/Target/RISCV/RISCVExpandAtomicPseudoInsts.cpp
@@ -86,6 +86,9 @@ bool RISCVExpandAtomicPseudo::expandMBB(MachineBasicBlock &MBB) {
 bool RISCVExpandAtomicPseudo::expandMI(MachineBasicBlock &MBB,
                                        MachineBasicBlock::iterator MBBI,
                                        MachineBasicBlock::iterator &NextMBBI) {
+  // RISCVInstrInfo::getInstSizeInBytes hard-codes the number of expanded
+  // instructions for each pseudo, and must be updated when adding new pseudos
+  // or changing existing ones.
   switch (MBBI->getOpcode()) {
   case RISCV::PseudoAtomicLoadNand32:
     return expandAtomicBinOp(MBB, MBBI, AtomicRMWInst::Nand, false, 32,

diff  --git a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
index 5dcd294cef04..504355fb8bf8 100644
--- a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
+++ b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
@@ -87,6 +87,9 @@ bool RISCVExpandPseudo::expandMBB(MachineBasicBlock &MBB) {
 bool RISCVExpandPseudo::expandMI(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MBBI,
                                  MachineBasicBlock::iterator &NextMBBI) {
+  // RISCVInstrInfo::getInstSizeInBytes hard-codes the number of expanded
+  // instructions for each pseudo, and must be updated when adding new pseudos
+  // or changing existing ones.
   switch (MBBI->getOpcode()) {
   case RISCV::PseudoLLA:
     return expandLoadLocalAddress(MBB, MBBI, NextMBBI);

diff  --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index dc212d9cde2e..d39ec505127c 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -471,6 +471,9 @@ unsigned RISCVInstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
   case TargetOpcode::KILL:
   case TargetOpcode::DBG_VALUE:
     return 0;
+  // These values are determined based on RISCVExpandAtomicPseudoInsts,
+  // RISCVExpandPseudoInsts and RISCVMCCodeEmitter, depending on where the
+  // pseudos are expanded.
   case RISCV::PseudoCALLReg:
   case RISCV::PseudoCALL:
   case RISCV::PseudoJump:
@@ -480,6 +483,26 @@ unsigned RISCVInstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
   case RISCV::PseudoLA_TLS_IE:
   case RISCV::PseudoLA_TLS_GD:
     return 8;
+  case RISCV::PseudoAtomicLoadNand32:
+  case RISCV::PseudoAtomicLoadNand64:
+    return 20;
+  case RISCV::PseudoMaskedAtomicSwap32:
+  case RISCV::PseudoMaskedAtomicLoadAdd32:
+  case RISCV::PseudoMaskedAtomicLoadSub32:
+    return 28;
+  case RISCV::PseudoMaskedAtomicLoadNand32:
+    return 32;
+  case RISCV::PseudoMaskedAtomicLoadMax32:
+  case RISCV::PseudoMaskedAtomicLoadMin32:
+    return 44;
+  case RISCV::PseudoMaskedAtomicLoadUMax32:
+  case RISCV::PseudoMaskedAtomicLoadUMin32:
+    return 36;
+  case RISCV::PseudoCmpXchg32:
+  case RISCV::PseudoCmpXchg64:
+    return 16;
+  case RISCV::PseudoMaskedCmpXchg32:
+    return 32;
   case TargetOpcode::INLINEASM:
   case TargetOpcode::INLINEASM_BR: {
     const MachineFunction &MF = *MI.getParent()->getParent();