[llvm] AMDGPU: Allocate special SGPRs before user SGPR arguments (PR #78234)

[Christudasan Devadasan via llvm-commits]

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@@ -2990,13 +2994,8 @@ SDValue SITargetLowering::LowerFormalArguments(
   }
 
   // Start adding system SGPRs.
-  if (IsEntryFunc) {
+  if (IsEntryFunc)
     allocateSystemSGPRs(CCInfo, MF, *Info, CallConv, IsGraphics);
-  } else {
-    CCInfo.AllocateReg(Info->getScratchRSrcReg());
-    if (!IsGraphics)
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cdevadas wrote:

There is an ongoing patch in the downstream where I enabled architected SGPRs for all callable functions. A patch will be posted in the upstream for gfx12 soon. With that, the call to `allocateSpecialInputSGPRs` needs to be enabled for gfx functions too. We need more clarity on how these special allocations should be treated for gfx functions.

https://github.com/llvm/llvm-project/pull/78234