[llvm] [Mips] Introduce ABI-specific register names and accessors (PR #224284)

[Jiaxun Yang via llvm-commits]

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@@ -1196,16 +1196,16 @@ bool MipsFastISel::processCallArgs(CallLoweringInfo &CLI,
         VA.isMemLoc()) {
       switch (VA.getLocMemOffset()) {
       case 0:
-        VA.convertToReg(Mips::A0);
+        VA.convertToReg(getABI().getArgReg(0, false));
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FlyGoat wrote:

getArgReg will return 64 bit SuperReg on n32/n64, here we want 32 bit reg unconditionally.

https://github.com/llvm/llvm-project/pull/224284