mirror of https://github.com/xemu-project/xemu.git
b3e22b2318
The new decoder is based on three principles: - use mostly table-driven decoding, using tables derived as much as possible from the Intel manual. Centralizing the decode the operands makes it more homogeneous, for example all immediates are signed. All modrm handling is in one function, and can be shared between SSE and ALU instructions (including XMM<->GPR instructions). The SSE/AVX decoder will also not have duplicated code between the 0F, 0F38 and 0F3A tables. - keep the code as "non-branchy" as possible. Generally, the code for the new decoder is more verbose, but the control flow is simpler. Conditionals are not nested and have small bodies. All instruction groups are resolved even before operands are decoded, and code generation is separated as much as possible within small functions that only handle one instruction each. - keep address generation and (for ALU operands) memory loads and writeback as much in common code as possible. All ALU operations for example are implemented as T0=f(T0,T1). For non-ALU instructions, read-modify-write memory operations are rare, but registers do not have TCGv equivalents: therefore, the common logic sets up pointer temporaries with the operands, while load and writeback are handled by gvec or by helpers. These principles make future code review and extensibility simpler, at the cost of having a relatively large amount of code in the form of this patch. Even EVEX should not be _too_ hard to implement (it's just a crazy large amount of possibilities). This patch introduces the main decoder flow, and integrates the old decoder with the new one. The old decoder takes care of parsing prefixes and then optionally drops to the new one. The changes to the old decoder are minimal and allow it to be replaced incrementally with the new one. There is a debugging mechanism through a "LIMIT" environment variable. In user-mode emulation, the variable is the number of instructions decoded by the new decoder before permanently switching to the old one. In system emulation, the variable is the highest opcode that is decoded by the new decoder (this is less friendly, but it's the best that can be done without requiring deterministic execution). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| .. | ||
| sysemu | ||
| user | ||
| bpt_helper.c | ||
| cc_helper.c | ||
| cc_helper_template.h | ||
| decode-new.c.inc | ||
| decode-new.h | ||
| emit.c.inc | ||
| excp_helper.c | ||
| fpu_helper.c | ||
| helper-tcg.h | ||
| int_helper.c | ||
| mem_helper.c | ||
| meson.build | ||
| misc_helper.c | ||
| mpx_helper.c | ||
| seg_helper.c | ||
| seg_helper.h | ||
| tcg-cpu.c | ||
| tcg-cpu.h | ||
| tcg-stub.c | ||
| translate.c | ||