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[CIR][Dialect] Add
convergent attribute to functions for SIMT langu…
…ages (llvm#840) Fix llvm#805. This PR includes end-to-end implementation. The `convergent` attribute is set depending on languages, which is wrapped as `langOpts.assumeFunctionsAreConvergent()`. Therefore, in ClangIR, every `cir.func` under `#cir.lang<opencl_c>` is set to be convergent. After lowering to LLVM IR, `PostOrderFunctionAttrs` pass will remove unnecessary `convergent` then. In other words, we will still see `convergent` on every function with `-O0`, but not with default optimization level. The test taken from `CodeGenOpenCL/convergent.cl` is a bit complicated. However, the core of it is that `convergent` is set properly for `convfun()` `non_convfun()` `f()` and `g()`. Merge of two `if` is more or less a result of generating the same LLVM IR as OG.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| // RUN: %clang_cc1 -fclangir -triple spirv64-unknown-unknown -emit-cir %s -o %t.cir | ||
| // RUN: FileCheck %s --input-file=%t.cir --check-prefix=CIR | ||
| // RUN: %clang_cc1 -fclangir -triple spirv64-unknown-unknown -emit-llvm %s -o %t.ll | ||
| // RUN: FileCheck %s --input-file=%t.ll --check-prefix=LLVM | ||
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| // In ClangIR for OpenCL, all functions should be marked convergent. | ||
| // In LLVM IR, it is initially assumed convergent, but can be deduced to not require it. | ||
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| // CIR: #fn_attr[[CONV_NOINLINE_ATTR:[0-9]*]] = #cir<extra({convergent = #cir.convergent, inline = #cir.inline<no> | ||
| // CIR-NEXT: #fn_attr[[CONV_DECL_ATTR:[0-9]*]] = #cir<extra({convergent = #cir.convergent | ||
| // CIR-NEXT: #fn_attr[[CONV_NOTHROW_ATTR:[0-9]*]] = #cir<extra({convergent = #cir.convergent, nothrow = #cir.nothrow | ||
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| __attribute__((noinline)) | ||
| void non_convfun(void) { | ||
| volatile int* p; | ||
| *p = 0; | ||
| } | ||
| // CIR: cir.func @non_convfun(){{.*}} extra(#fn_attr[[CONV_NOINLINE_ATTR]]) | ||
| // LLVM: define{{.*}} spir_func void @non_convfun() local_unnamed_addr #[[NON_CONV_ATTR:[0-9]+]] | ||
| // LLVM: ret void | ||
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| // External functions should be assumed convergent. | ||
| void f(void); | ||
| // CIR: cir.func{{.+}} @f(){{.*}} extra(#fn_attr[[CONV_DECL_ATTR]]) | ||
| // LLVM: declare {{.+}} spir_func void @f() local_unnamed_addr #[[CONV_ATTR:[0-9]+]] | ||
| void g(void); | ||
| // CIR: cir.func{{.+}} @g(){{.*}} extra(#fn_attr[[CONV_DECL_ATTR]]) | ||
| // LLVM: declare {{.+}} spir_func void @g() local_unnamed_addr #[[CONV_ATTR]] | ||
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| // Test two if's are merged and non_convfun duplicated. | ||
| void test_merge_if(int a) { | ||
| if (a) { | ||
| f(); | ||
| } | ||
| non_convfun(); | ||
| if (a) { | ||
| g(); | ||
| } | ||
| } | ||
| // CIR: cir.func @test_merge_if{{.*}} extra(#fn_attr[[CONV_NOTHROW_ATTR]]) | ||
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| // The LLVM IR below is equivalent to: | ||
| // if (a) { | ||
| // f(); | ||
| // non_convfun(); | ||
| // g(); | ||
| // } else { | ||
| // non_convfun(); | ||
| // } | ||
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| // LLVM-LABEL: define{{.*}} spir_func void @test_merge_if | ||
| // LLVM: %[[tobool:.+]] = icmp eq i32 %[[ARG:.+]], 0 | ||
| // LLVM: br i1 %[[tobool]], label %[[if_end3_critedge:[^,]+]], label %[[if_then:[^,]+]] | ||
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| // LLVM: [[if_end3_critedge]]: | ||
| // LLVM: tail call spir_func void @non_convfun() | ||
| // LLVM: br label %[[if_end3:[^,]+]] | ||
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| // LLVM: [[if_then]]: | ||
| // LLVM: tail call spir_func void @f() | ||
| // LLVM: tail call spir_func void @non_convfun() | ||
| // LLVM: tail call spir_func void @g() | ||
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| // LLVM: br label %[[if_end3]] | ||
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| // LLVM: [[if_end3]]: | ||
| // LLVM: ret void | ||
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| void convfun(void) __attribute__((convergent)); | ||
| // CIR: cir.func{{.+}} @convfun(){{.*}} extra(#fn_attr[[CONV_DECL_ATTR]]) | ||
| // LLVM: declare {{.+}} spir_func void @convfun() local_unnamed_addr #[[CONV_ATTR]] | ||
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| // Test two if's are not merged. | ||
| void test_no_merge_if(int a) { | ||
| if (a) { | ||
| f(); | ||
| } | ||
| convfun(); | ||
| if(a) { | ||
| g(); | ||
| } | ||
| } | ||
| // CIR: cir.func @test_no_merge_if{{.*}} extra(#fn_attr[[CONV_NOTHROW_ATTR]]) | ||
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| // LLVM-LABEL: define{{.*}} spir_func void @test_no_merge_if | ||
| // LLVM: %[[tobool:.+]] = icmp eq i32 %[[ARG:.+]], 0 | ||
| // LLVM: br i1 %[[tobool]], label %[[if_end:[^,]+]], label %[[if_then:[^,]+]] | ||
| // LLVM: [[if_then]]: | ||
| // LLVM: tail call spir_func void @f() | ||
| // LLVM-NOT: call spir_func void @convfun() | ||
| // LLVM-NOT: call spir_func void @g() | ||
| // LLVM: br label %[[if_end]] | ||
| // LLVM: [[if_end]]: | ||
| // LLVM-NOT: phi i1 | ||
| // LLVM: tail call spir_func void @convfun() | ||
| // LLVM: br i1 %[[tobool]], label %[[if_end3:[^,]+]], label %[[if_then2:[^,]+]] | ||
| // LLVM: [[if_then2]]: | ||
| // LLVM: tail call spir_func void @g() | ||
| // LLVM: br label %[[if_end3:[^,]+]] | ||
| // LLVM: [[if_end3]]: | ||
| // LLVM: ret void | ||
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| // LLVM attribute definitions. | ||
| // LLVM-NOT: attributes #[[NON_CONV_ATTR]] = { {{.*}}convergent{{.*}} } | ||
| // LLVM: attributes #[[CONV_ATTR]] = { {{.*}}convergent{{.*}} } |