forked from OSchip/llvm-project
5ecd81aab0
specially handle SETB_C* pseudo instructions. Summary: While the logic here is somewhat similar to the arithmetic lowering, it is different enough that it made sense to have its own function. I actually tried a bunch of different optimizations here and none worked well so I gave up and just always do the arithmetic based lowering. Looking at code from the PR test case, we actually pessimize a bunch of code when generating these. Because SETB_C* pseudo instructions clobber EFLAGS, we end up creating a bunch of copies of EFLAGS to feed multiple SETB_C* pseudos from a single set of EFLAGS. This in turn causes the lowering code to ruin all the clever code generation that SETB_C* was hoping to achieve. None of this is needed. Whenever we're generating multiple SETB_C* instructions from a single set of EFLAGS we should instead generate a single maximally wide one and extract subregs for all the different desired widths. That would result in substantially better code generation. But this patch doesn't attempt to address that. The test case from the PR is included as well as more directed testing of the specific lowering pattern used for these pseudos. Reviewers: craig.topper Subscribers: sanjoy, mcrosier, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D46799 llvm-svn: 332389 |
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| Analysis | ||
| AsmParser | ||
| BinaryFormat | ||
| Bitcode | ||
| CodeGen | ||
| DebugInfo | ||
| Demangle | ||
| ExecutionEngine | ||
| FuzzMutate | ||
| Fuzzer | ||
| IR | ||
| IRReader | ||
| LTO | ||
| LineEditor | ||
| Linker | ||
| MC | ||
| Object | ||
| ObjectYAML | ||
| Option | ||
| Passes | ||
| ProfileData | ||
| Support | ||
| TableGen | ||
| Target | ||
| Testing | ||
| ToolDrivers | ||
| Transforms | ||
| WindowsManifest | ||
| XRay | ||
| CMakeLists.txt | ||
| LLVMBuild.txt | ||