[clang] [Clang] [WIP] Added builtin_alloca support for OpenCL1.2 and below (PR #95750)

[Vikash Gupta via cfe-commits]

================
@@ -0,0 +1,86 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
+// RUN: %clang_cc1 %s -O0 -triple amdgcn-amd-amdhsa -cl-std=CL1.2 -emit-llvm -o - | FileCheck --check-prefix=OPENCL12 %s
+// RUN: %clang_cc1 %s -O0 -triple amdgcn-amd-amdhsa -cl-std=CL2.0 -emit-llvm -o - | FileCheck --check-prefix=OPENCL20 %s
+// RUN: %clang_cc1 %s -O0 -triple amdgcn-amd-amdhsa -cl-std=CL3.0 -emit-llvm -o - | FileCheck --check-prefix=OPENCL30 %s
+// RUN: %clang_cc1 %s -O0 -triple amdgcn-amd-amdhsa -cl-std=CL3.0 -cl-ext=+__opencl_c_generic_address_space -emit-llvm -o - | FileCheck --check-prefix=OPENCL30-EXT %s
+
+// OPENCL12-LABEL: define dso_local ptr addrspace(5) @test1(
+// OPENCL12-SAME: ) #[[ATTR0:[0-9]+]] {
+// OPENCL12-NEXT:  [[ENTRY:.*:]]
+// OPENCL12-NEXT:    [[ALLOC_PTR:%.*]] = alloca ptr addrspace(5), align 4, addrspace(5)
+// OPENCL12-NEXT:    [[TMP0:%.*]] = alloca i8, i64 128, align 8, addrspace(5)
+// OPENCL12-NEXT:    store ptr addrspace(5) [[TMP0]], ptr addrspace(5) [[ALLOC_PTR]], align 4
+// OPENCL12-NEXT:    [[TMP1:%.*]] = load ptr addrspace(5), ptr addrspace(5) [[ALLOC_PTR]], align 4
+// OPENCL12-NEXT:    ret ptr addrspace(5) [[TMP1]]
+//
+// OPENCL20-LABEL: define dso_local ptr @test1(
+// OPENCL20-SAME: ) #[[ATTR0:[0-9]+]] {
+// OPENCL20-NEXT:  [[ENTRY:.*:]]
+// OPENCL20-NEXT:    [[ALLOC_PTR:%.*]] = alloca ptr, align 8, addrspace(5)
+// OPENCL20-NEXT:    [[TMP0:%.*]] = alloca i8, i64 128, align 8, addrspace(5)
+// OPENCL20-NEXT:    [[TMP1:%.*]] = addrspacecast ptr addrspace(5) [[TMP0]] to ptr
+// OPENCL20-NEXT:    store ptr [[TMP1]], ptr addrspace(5) [[ALLOC_PTR]], align 8
+// OPENCL20-NEXT:    [[TMP2:%.*]] = load ptr, ptr addrspace(5) [[ALLOC_PTR]], align 8
+// OPENCL20-NEXT:    ret ptr [[TMP2]]
+//
+// OPENCL30-LABEL: define dso_local ptr addrspace(5) @test1(
+// OPENCL30-SAME: ) #[[ATTR0:[0-9]+]] {
+// OPENCL30-NEXT:  [[ENTRY:.*:]]
+// OPENCL30-NEXT:    [[ALLOC_PTR:%.*]] = alloca ptr addrspace(5), align 4, addrspace(5)
+// OPENCL30-NEXT:    [[TMP0:%.*]] = alloca i8, i64 128, align 8, addrspace(5)
+// OPENCL30-NEXT:    store ptr addrspace(5) [[TMP0]], ptr addrspace(5) [[ALLOC_PTR]], align 4
+// OPENCL30-NEXT:    [[TMP1:%.*]] = load ptr addrspace(5), ptr addrspace(5) [[ALLOC_PTR]], align 4
+// OPENCL30-NEXT:    ret ptr addrspace(5) [[TMP1]]
+//
+// OPENCL30-EXT-LABEL: define dso_local ptr @test1(
+// OPENCL30-EXT-SAME: ) #[[ATTR0:[0-9]+]] {
+// OPENCL30-EXT-NEXT:  [[ENTRY:.*:]]
+// OPENCL30-EXT-NEXT:    [[ALLOC_PTR:%.*]] = alloca ptr, align 8, addrspace(5)
+// OPENCL30-EXT-NEXT:    [[TMP0:%.*]] = alloca i8, i64 128, align 8, addrspace(5)
+// OPENCL30-EXT-NEXT:    [[TMP1:%.*]] = addrspacecast ptr addrspace(5) [[TMP0]] to ptr
+// OPENCL30-EXT-NEXT:    store ptr [[TMP1]], ptr addrspace(5) [[ALLOC_PTR]], align 8
+// OPENCL30-EXT-NEXT:    [[TMP2:%.*]] = load ptr, ptr addrspace(5) [[ALLOC_PTR]], align 8
+// OPENCL30-EXT-NEXT:    ret ptr [[TMP2]]
+//
+float* test1() {
+    float* alloc_ptr = (float*)__builtin_alloca(32 * sizeof(int));
----------------
vg0204 wrote:

Currently, I made it as such for opencl1.2 & below, it will return private pointer so no cast would be seen if __private qualifier is used. But for openCL2.0 & above, it returns a pointer to generic address space, so test2 becomes problematic as initializing '__private void *__private' with an expression of type '__generic void *' changes address space of pointer.

https://github.com/llvm/llvm-project/pull/95750