[llvm] [AMDGPU] Add AMDGPU-specific module splitting (PR #89245)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,98 @@
+; RUN: llvm-split -o %t %s -j 3 -mtriple amdgcn-amd-amdhsa -amdgpu-module-splitting-large-kernel-threshold=1.2 -amdgpu-module-splitting-large-kernel-merge-overlap=0.5
+; RUN: llvm-dis -o - %t0 | FileCheck --check-prefix=CHECK0 %s
+; RUN: llvm-dis -o - %t1 | FileCheck --check-prefix=CHECK1 %s
+; RUN: llvm-dis -o - %t2 | FileCheck --check-prefix=CHECK2 %s
+
+; RUN: llvm-split -o %t.nolarge %s -j 3 -mtriple amdgcn-amd-amdhsa -amdgpu-module-splitting-large-kernel-threshold=0
+; RUN: llvm-dis -o - %t.nolarge0 | FileCheck --check-prefix=NOLARGEKERNELS-CHECK0 %s
+; RUN: llvm-dis -o - %t.nolarge1 | FileCheck --check-prefix=NOLARGEKERNELS-CHECK1 %s
+; RUN: llvm-dis -o - %t.nolarge2 | FileCheck --check-prefix=NOLARGEKERNELS-CHECK2 %s
+
+; 2 kernels (A/B) are large and share all their dependencies.
+; They should go in the same partition, the remaining kernel should
+; go somewhere else, and one partition should be empty.
+;
+; Also check w/o large kernels processing to verify they are indeed handled
+; differently.
+
+; CHECK0-NOT: define
+
+; CHECK1-NOT: define
+; CHECK1: define internal void @HelperC()
+; CHECK1: define amdgpu_kernel void @C
+; CHECK1-NOT: define
+
+; CHECK2-NOT: define
+; CHECK2: define internal void @large2()
+; CHECK2: define internal void @large1()
+; CHECK2: define internal void @large0()
+; CHECK2: define internal void @HelperA()
+; CHECK2: define internal void @HelperB()
+; CHECK2: define amdgpu_kernel void @A
+; CHECK2: define amdgpu_kernel void @B
+; CHECK2-NOT: define
+
+; NOLARGEKERNELS-CHECK0-NOT: define
+; NOLARGEKERNELS-CHECK0: define internal void @HelperC()
+; NOLARGEKERNELS-CHECK0: define amdgpu_kernel void @C
+; NOLARGEKERNELS-CHECK0-NOT: define
+
+; NOLARGEKERNELS-CHECK1: define internal void @large2()
+; NOLARGEKERNELS-CHECK1: define internal void @large1()
+; NOLARGEKERNELS-CHECK1: define internal void @large0()
+; NOLARGEKERNELS-CHECK1: define internal void @HelperB()
+; NOLARGEKERNELS-CHECK1: define amdgpu_kernel void @B
+
+; NOLARGEKERNELS-CHECK2: define internal void @large2()
+; NOLARGEKERNELS-CHECK2: define internal void @large1()
+; NOLARGEKERNELS-CHECK2: define internal void @large0()
+; NOLARGEKERNELS-CHECK2: define internal void @HelperA()
+; NOLARGEKERNELS-CHECK2: define amdgpu_kernel void @A
+
+define internal void @large2() {
+  store i32 42, ptr undef
----------------
arsenm wrote:

```suggestion
  store volatile 32 42, ptr null
```

https://github.com/llvm/llvm-project/pull/89245