forked from OSchip/llvm-project
b2c65beb14
SAHF/LAHF instructions are always available in 32-bit mode. Early 64-bit capable CPUs made the undefined opcodes in 64-bit mode. This was changed on later CPUs. We have a feature flag to control our usage of these instructions. This feature flag is hooked up to a clang command line option -msahf/-mno-sahf specifically to give control of the 64-bit mode behavior. In the backend X86Subtarget constructor we were explicitly forcing +sahf into the feature flag string if we were not compiling for 64-bit mode. This was intended to make the predicates always allow the instructions outside of 64-bit mode. Unfortunately, the way it was placed into the string allowed -mno-sahf from clang to disable SAHF instructions in 32-bit mode. This causes an assertion to fire if you compile a floating point comparison with something like "-march=pentium -mno-sahf" as our floating point comparison handling on CPUs that don't support FCOMI/FUCOMI instructions requires SAHF. To fix this, this commit restricts the feature flag to only apply to 64-bit mode by ignoring the flag outside 64-bit mode in X86Subtarget::hasLAHFSAHF(). This way we don't need to mess with the feature string at all. |
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| AArch64 | ||
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| ARC | ||
| ARM | ||
| AVR | ||
| BPF | ||
| Generic | ||
| Hexagon | ||
| Inputs | ||
| Lanai | ||
| MIR | ||
| MSP430 | ||
| Mips | ||
| NVPTX | ||
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| RISCV | ||
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| SystemZ | ||
| Thumb | ||
| Thumb2 | ||
| VE | ||
| WebAssembly | ||
| WinCFGuard | ||
| WinEH | ||
| X86 | ||
| XCore | ||