mirror of https://github.com/proxmox/mirror_qemu
f8c0fd9804
On hppa the Instruction Address Offset Queue (IAOQ) registers specifies the next to-be-executed instructions addresses. Each generated TB writes those registers at least once, so those registers are used heavily in generated code. Looking at the generated assembly, for a x86-64 host this code to write the address $0x7ffe826f into iaoq_f is generated: 0x7f73e8000184: c7 85 d4 01 00 00 6f 82 movl $0x7ffe826f, 0x1d4(%rbp) 0x7f73e800018c: fe 7f 0x7f73e800018e: c7 85 d8 01 00 00 73 82 movl $0x7ffe8273, 0x1d8(%rbp) 0x7f73e8000196: fe 7f With the trivial change, by moving the variables iaoq_f and iaoq_b to the top of struct CPUArchState, the offset to %rbp is reduced (from 0x1d4 to 0), which allows the x86-64 tcg to generate 3 bytes less of generated code per move instruction: 0x7fc1e800018c: c7 45 00 6f 82 fe 7f movl $0x7ffe826f, (%rbp) 0x7fc1e8000193: c7 45 04 73 82 fe 7f movl $0x7ffe8273, 4(%rbp) Overall this is a reduction of generated code (not a reduction of number of instructions). A test run with checks the generated code size by running "/bin/ls" with qemu-user shows that the code size shrinks from 1616767 to 1569273 bytes, which is ~97% of the former size. Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Helge Deller <deller@gmx.de> Cc: qemu-stable@nongnu.org |
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| .. | ||
| Kconfig | ||
| cpu-param.h | ||
| cpu-qom.h | ||
| cpu.c | ||
| cpu.h | ||
| fpu_helper.c | ||
| gdbstub.c | ||
| helper.c | ||
| helper.h | ||
| insns.decode | ||
| int_helper.c | ||
| machine.c | ||
| mem_helper.c | ||
| meson.build | ||
| op_helper.c | ||
| sys_helper.c | ||
| trace-events | ||
| trace.h | ||
| translate.c | ||