diff options
Diffstat (limited to 'source/slang/slang-ir-peephole.cpp')
| -rw-r--r-- | source/slang/slang-ir-peephole.cpp | 37 |
1 files changed, 29 insertions, 8 deletions
diff --git a/source/slang/slang-ir-peephole.cpp b/source/slang/slang-ir-peephole.cpp index 8d6685212..79dfc1360 100644 --- a/source/slang/slang-ir-peephole.cpp +++ b/source/slang/slang-ir-peephole.cpp @@ -1041,7 +1041,7 @@ struct PeepholeContext : InstPassBase continue; SLANG_ASSERT(terminator->getArgCount() > paramIndex); auto arg = terminator->getArg(paramIndex); - if (arg->getOp() == kIROp_Undefined) + if (as<IRUndefined>(arg)) continue; if (argValue == nullptr) argValue = arg; @@ -1268,14 +1268,18 @@ struct PeepholeContext : InstPassBase } case kIROp_Load: { - // Load from undef is undef. - if (as<IRLoad>(inst)->getPtr()->getOp() == kIROp_Undefined) + // An attempt to load from an undefined pointer value + // is undefined behavior and the resulting value is poison + // (the value should typically contaminate instructions that + // use it, rendering them as poisonous). + // + if (as<IRUndefined>(as<IRLoad>(inst)->getPtr())) { IRBuilder builder(module); IRBuilderSourceLocRAII srcLocRAII(&builder, inst->sourceLoc); builder.setInsertBefore(inst); - auto undef = builder.emitUndefined(inst->getDataType()); + auto undef = builder.emitPoison(inst->getDataType()); inst->replaceUsesWith(undef); maybeRemoveOldInst(inst); changed = true; @@ -1284,8 +1288,17 @@ struct PeepholeContext : InstPassBase } case kIROp_Store: { - // Store undef is no-op. - if (as<IRStore>(inst)->getVal()->getOp() == kIROp_Undefined) + // An attempt to store to an undefined pointer value is + // undefined behavior (just like a load), so we can conveniently + // decide to implement that behavior as a no-op. + // + // TODO: While it is not the responsibility of a pass like this + // to diagnose errors (that is the front-end's job), it might + // be best to replace an invalid `store` like this with an + // instruction that represents a "panic" or similar exceptional + // situation. + // + if (as<IRUndefined>(as<IRStore>(inst)->getVal())) { maybeRemoveOldInst(inst); changed = true; @@ -1294,8 +1307,16 @@ struct PeepholeContext : InstPassBase } case kIROp_DebugValue: { - // Update debug value with undef is no-op. - if (as<IRDebugValue>(inst)->getValue()->getOp() == kIROp_Undefined) + // Attempting to update the debug value of a variable with an + // undefined value will be treated as a no-op (meaning that the + // contents of the variable, as perceived by the user, will not + // change). + // + // TODO: We should probably validate that this is a reasonable + // behavior. In many cases a debugger user might like to have an + // indication of when the contents of their variable are undefined. + // + if (as<IRUndefined>(as<IRDebugValue>(inst)->getValue())) { maybeRemoveOldInst(inst); changed = true; |