b9c77542e2
The `assume` attribute is a way to provide additional, arbitrary information to the optimizer. For now, assumptions are restricted to strings which will be accumulated for a function and emitted as comma separated string function attribute. The key of the LLVM-IR function attribute is `llvm.assume`. Similar to `llvm.assume` and `__builtin_assume`, the `assume` attribute provides a user defined assumption to the compiler. A follow up patch will introduce an LLVM-core API to query the assumptions attached to a function. We also expect to add more options, e.g., expression arguments, to the `assume` attribute later on. The `omp [begin] asssumes` pragma will leverage this attribute and expose the functionality in the absence of OpenMP. Reviewed By: aaron.ballman Differential Revision: https://reviews.llvm.org/D91979
59 lines
1.8 KiB
C
59 lines
1.8 KiB
C
// RUN: %clang_cc1 -emit-llvm -triple i386-linux-gnu %s -o - | FileCheck %s
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// RUN: %clang_cc1 -x c -emit-pch -o %t %s
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// RUN: %clang_cc1 -include-pch %t %s -emit-llvm -o - | FileCheck %s
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// TODO: for "foo" and "bar", "after" is not added as it appears "after" the first use or definition respectively. There might be a way to allow that.
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// CHECK: define{{.*}} void @bar() #0
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// CHECK: define{{.*}} void @baz() #1
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// CHECK: declare{{.*}} void @foo() #2
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// CHECK: attributes #0
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// CHECK-SAME: "llvm.assume"="bar:before1,bar:before2,bar:before3,bar:def1,bar:def2"
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// CHECK: attributes #1
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// CHECK-SAME: "llvm.assume"="baz:before1,baz:before2,baz:before3,baz:def1,baz:def2,baz:after"
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// CHECK: attributes #2
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// CHECK-SAME: "llvm.assume"="foo:before1,foo:before2,foo:before3"
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#ifndef HEADER
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#define HEADER
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/// foo: declarations only
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__attribute__((assume("foo:before1"))) void foo(void);
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__attribute__((assume("foo:before2")))
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__attribute__((assume("foo:before3"))) void
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foo(void);
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/// baz: static function declarations and a definition
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__attribute__((assume("baz:before1"))) static void baz(void);
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__attribute__((assume("baz:before2")))
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__attribute__((assume("baz:before3"))) static void
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baz(void);
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// Definition
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__attribute__((assume("baz:def1,baz:def2"))) static void baz(void) { foo(); }
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__attribute__((assume("baz:after"))) static void baz(void);
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/// bar: external function declarations and a definition
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__attribute__((assume("bar:before1"))) void bar(void);
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__attribute__((assume("bar:before2")))
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__attribute__((assume("bar:before3"))) void
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bar(void);
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// Definition
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__attribute__((assume("bar:def1,bar:def2"))) void bar(void) { baz(); }
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__attribute__((assume("bar:after"))) void bar(void);
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/// back to foo
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__attribute__((assume("foo:after"))) void foo(void);
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#endif
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