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| author | Kazu Hirata <kazu@google.com> | 2023-01-25 20:54:43 -0800 |
|---|---|---|
| committer | Kazu Hirata <kazu@google.com> | 2023-01-25 20:54:43 -0800 |
| commit | cdc2a0473e90732245387344248b5487778f9b6f (patch) | |
| tree | 2aa47a65f633284cd5618484fc1dd33dc4ce883d /llvm/lib/CodeGen/MachineCopyPropagation.cpp | |
| parent | 3b53c6020052215be97898a4312fc41ca626a0ad (diff) | |
| download | llvm-cdc2a0473e90732245387344248b5487778f9b6f.zip llvm-cdc2a0473e90732245387344248b5487778f9b6f.tar.gz llvm-cdc2a0473e90732245387344248b5487778f9b6f.tar.bz2 | |
[Mips] Simplify loadImmediate (NFC)
loadImmediate computes ShiftAmount in an unnecessarily complicated
manner. We just need to know the minimum right shift amount to bring
the immediate down to an unsigned 16-bit value, so
unsigned ShiftAmount = llvm::bit_width((uint64_t)ImmValue) - 16;
is sufficient. In other words, the following are all equivalent:
unsigned ShiftAmount = FirstSet - (15 - (LastSet - FirstSet));
unsigned ShiftAmount = llvm::countr_zero(IV) - (15 - (63 - llvm::countl_zero(IV) - llvm::countr_zero(IV)));
unsigned ShiftAmount = llvm::countr_zero(IV) - 15 + (63 - llvm::countl_zero(IV) - llvm::countr_zero(IV));
unsigned ShiftAmount = 48 - llvm::countl_zero(IV);
unsigned ShiftAmount = 64 - llvm::countl_zero(IV) - 16;
unsigned ShiftAmount = llvm::bit_width(IV) - 16;
where IV represents (uint64)ImmValue. I've also checked the
equivalence empirically up to 2u << 32.
Diffstat (limited to 'llvm/lib/CodeGen/MachineCopyPropagation.cpp')
0 files changed, 0 insertions, 0 deletions