forked from OSchip/llvm-project
4a5f522d4d
MachineInstr::isIdenticalTo has a lot of logic for dealing with register Defs (i.e. deciding whether to take them into account or ignore them). This logic gets things wrong in some obscure cases, for instance if an operand is not a Def for both the current MI and the one we are comparing to. I'm not sure if it's possible for this to happen for regular register operands, but it may happen in the ARM backend for special operands which use sentinel values for the register (i.e. 0, which is neither a physical register nor a virtual one). This causes MachineInstrExpressionTrait::isEqual (which uses MachineInstr::isIdenticalTo) to return true for the following instructions, which are the same except for the fact that one sets the flags and the other one doesn't: %1114 = ADDrsi %1113, %216, 17, 14, _, def _ %1115 = ADDrsi %1113, %216, 17, 14, _, _ OTOH, MachineInstrExpressionTrait::getHashValue returns different values for the 2 instructions due to the different isDef on the last operand. In practice this means that when trying to add those instructions to a DenseMap, they will be considered different because of their different hash values, but when growing the map we might get an assertion while copying from the old buckets to the new buckets because isEqual misleadingly returns true. This patch makes sure that isEqual and getHashValue agree, by improving the checks in MachineInstr::isIdenticalTo when we are ignoring virtual register definitions (which is what the Trait uses). Firstly, instead of checking isPhysicalRegister, we use !isVirtualRegister, so that we cover both physical registers and sentinel values. Secondly, instead of checking MachineOperand::isReg, we use MachineOperand::isIdenticalTo, which checks isReg, isSubReg and isDef, which are the same values that the hash function uses to compute the hash. Note that the function is symmetric with this change, since if the current operand is not a Def, we check MachineOperand::isIdenticalTo, which returns false if the operands have different isDef's. Differential Revision: https://reviews.llvm.org/D38789 llvm-svn: 315579 |
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| .. | ||
| GlobalISel | ||
| CMakeLists.txt | ||
| DIEHashTest.cpp | ||
| LowLevelTypeTest.cpp | ||
| MachineInstrBundleIteratorTest.cpp | ||
| MachineInstrTest.cpp | ||
| MachineOperandTest.cpp | ||
| ScalableVectorMVTsTest.cpp | ||