[llvm] [AMDGPU] Add intrinsic exposing s_alloc_vgpr (PR #163951)

[Diana Picus via llvm-commits]

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@@ -391,6 +391,17 @@ def int_amdgcn_s_wait_loadcnt        : AMDGPUWaitIntrinsic;
 def int_amdgcn_s_wait_samplecnt      : AMDGPUWaitIntrinsic;
 def int_amdgcn_s_wait_storecnt       : AMDGPUWaitIntrinsic;
 
+// Force the VGPR allocation of the current wave to (at least) the given value.
+// The actual number of allocated VGPRs may be rounded up to match hardware
+// block boundaries.
+// It is the responsibility of the calling code to ensure it does not allocate
+// below the VGPR requirements of the current shader.
+def int_amdgcn_s_alloc_vgpr :
+  Intrinsic<
+    [llvm_i1_ty], // Returns true if the allocation succeeded, false otherwise.
+    [llvm_i32_ty], // The number of VGPRs to allocate.
+    [NoUndef<RetIndex>, IntrNoMem, IntrHasSideEffects, IntrConvergent, IntrWillReturn, IntrNoCallback, IntrNoFree]>;
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rovka wrote:

Absolutely, thanks!

https://github.com/llvm/llvm-project/pull/163951