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Consider the case where d and a refer to the same PowerPC register, which is known to hold an immediate value by the RegCache. We place a ReadWrite constraint on this register and bind it to an x86 register. The RegCache then allocates a new register, initializes it with the immediate, and returns a RCX64Reg for both d and a. At this point information about the immediate value becomes unreachable. In the case of subfx, this generates suboptimal code: Before 1: BF 1E 00 00 00 mov edi,1Eh <- done by RegCache 8B C7 mov eax,edi 8B FE mov edi,esi 2B F8 sub edi,eax Before 2: BE 00 AC 3F 80 mov esi,803FAC00h <- done by RegCache 8B C6 mov eax,esi 8B 75 EC mov esi,dword ptr [rbp-14h] 2B F0 sub esi,eax The solution is to explicitly handle the constant a case before having the RegCache allocate registers for us. After 1: 8D 7E E2 lea edi,[rsi-1Eh] After 2: 8B 75 EC mov esi,dword ptr [rbp-14h] 81 EE 00 AC 3F 80 sub esi,803FAC00h |
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| Android | ||
| Core | ||
| DSPSpy | ||
| DSPTool | ||
| PCH | ||
| UnitTests | ||
| VSProps | ||
| .clang-format | ||
| CMakeLists.txt | ||
| dolphin-emu.sln | ||