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clang: Add pragma clang fp reciprocal (#68267)
Just follow along with the reassociate pragma. This allows locally setting the arcp fast math flag. Previously you could only access this through the global -freciprocal-math. Fixes #64798
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| // RUN: %clang_cc1 -O3 -triple %itanium_abi_triple -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK,DEFAULT %s | ||
| // RUN: %clang_cc1 -O3 -triple %itanium_abi_triple -freciprocal-math -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK,FLAG %s | ||
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| float base(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z4basefff | ||
| // FLAG: %[[A:.+]] = fdiv arcp float %b, %c | ||
| // FLAG: %[[M:.+]] = fdiv arcp float %[[A]], %b | ||
| // FLAG-NEXT: fadd arcp float %[[M]], %c | ||
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| // DEFAULT: %[[A:.+]] = fdiv float %b, %c | ||
| // DEFAULT: %[[M:.+]] = fdiv float %[[A]], %b | ||
| // DEFAULT-NEXT: fadd float %[[M]], %c | ||
| a = b / c; | ||
| return a / b + c; | ||
| } | ||
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| // Simple case | ||
| float fp_recip_simple(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z15fp_recip_simplefff | ||
| // CHECK: %[[A:.+]] = fdiv arcp float %b, %c | ||
| // CHECK: %[[M:.+]] = fdiv arcp float %[[A]], %b | ||
| // CHECK-NEXT: fadd arcp float %[[M]], %c | ||
| #pragma clang fp reciprocal(on) | ||
| a = b / c; | ||
| return a / b + c; | ||
| } | ||
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| // Test interaction with -freciprocal-math | ||
| float fp_recip_disable(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z16fp_recip_disablefff | ||
| // CHECK: %[[A:.+]] = fdiv float %b, %c | ||
| // CHECK: %[[M:.+]] = fdiv float %[[A]], %b | ||
| // CHECK-NEXT: fadd float %[[M]], %c | ||
| #pragma clang fp reciprocal(off) | ||
| a = b / c; | ||
| return a / b + c; | ||
| } | ||
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| float fp_recip_with_reassoc_simple(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z28fp_recip_with_reassoc_simplefff | ||
| // CHECK: %[[A:.+]] = fmul reassoc arcp float %b, %c | ||
| // CHECK: %[[M:.+]] = fdiv reassoc arcp float %b, %[[A]] | ||
| // CHECK-NEXT: fadd reassoc arcp float %[[M]], %c | ||
| #pragma clang fp reciprocal(on) reassociate(on) | ||
| a = b / c; | ||
| return a / b + c; | ||
| } | ||
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| // arcp pragma should only apply to its scope | ||
| float fp_recip_scoped(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z15fp_recip_scopedfff | ||
| // DEFAULT: %[[M:.+]] = fdiv float %a, %b | ||
| // DEFAULT-NEXT: fadd float %[[M]], %c | ||
| // FLAG: %[[M:.+]] = fdiv arcp float %a, %b | ||
| // FLAG-NEXT: fadd arcp float %[[M]], %c | ||
| { | ||
| #pragma clang fp reciprocal(on) | ||
| } | ||
| return a / b + c; | ||
| } | ||
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| // arcp pragma should apply to templates as well | ||
| class Foo {}; | ||
| Foo operator+(Foo, Foo); | ||
| template <typename T> | ||
| T template_recip(T a, T b, T c) { | ||
| #pragma clang fp reciprocal(on) | ||
| return ((a / b) - c) + c; | ||
| } | ||
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| float fp_recip_template(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z17fp_recip_templatefff | ||
| // CHECK: %[[A1:.+]] = fdiv arcp float %a, %b | ||
| // CHECK-NEXT: %[[A2:.+]] = fsub arcp float %[[A1]], %c | ||
| // CHECK-NEXT: fadd arcp float %[[A2]], %c | ||
| return template_recip<float>(a, b, c); | ||
| } | ||
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| // File Scoping should work across functions | ||
| #pragma clang fp reciprocal(on) | ||
| float fp_file_scope_on(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z16fp_file_scope_onfff | ||
| // CHECK: %[[M1:.+]] = fdiv arcp float %a, %c | ||
| // CHECK-NEXT: %[[M2:.+]] = fdiv arcp float %b, %c | ||
| // CHECK-NEXT: fadd arcp float %[[M1]], %[[M2]] | ||
| return (a / c) + (b / c); | ||
| } | ||
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| // Inner pragma has precedence | ||
| float fp_file_scope_stop(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z18fp_file_scope_stopfff | ||
| // CHECK: %[[A:.+]] = fdiv arcp float %a, %a | ||
| // CHECK: %[[M1:.+]] = fdiv float %[[A]], %c | ||
| // CHECK-NEXT: %[[M2:.+]] = fdiv float %b, %c | ||
| // CHECK-NEXT: fsub float %[[M1]], %[[M2]] | ||
| a = a / a; | ||
| { | ||
| #pragma clang fp reciprocal(off) | ||
| return (a / c) - (b / c); | ||
| } | ||
| } | ||
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| #pragma clang fp reciprocal(off) | ||
| float fp_recip_off(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z12fp_recip_offfff | ||
| // CHECK: %[[D1:.+]] = fdiv float %a, %c | ||
| // CHECK-NEXT: %[[D2:.+]] = fdiv float %b, %c | ||
| // CHECK-NEXT: fadd float %[[D1]], %[[D2]] | ||
| return (a / c) + (b / c); | ||
| } | ||
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| // Takes latest flag | ||
| float fp_recip_many(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z13fp_recip_manyfff | ||
| // CHECK: %[[D1:.+]] = fdiv arcp float %a, %c | ||
| // CHECK-NEXT: %[[D2:.+]] = fdiv arcp float %b, %c | ||
| // CHECK-NEXT: fadd arcp float %[[D1]], %[[D2]] | ||
| #pragma clang fp reciprocal(off) reciprocal(on) | ||
| return (a / c) + (b / c); | ||
| } | ||
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| // Pragma does not propagate through called functions | ||
| float helper_func(float a, float b, float c) { return a + b + c; } | ||
| float fp_recip_call_helper(float a, float b, float c) { | ||
| // CHECK-LABEL: _Z20fp_recip_call_helperfff | ||
| // CHECK: %[[S1:.+]] = fadd float %a, %b | ||
| // CHECK-NEXT: fadd float %[[S1]], %c | ||
| #pragma clang fp reciprocal(on) | ||
| return helper_func(a, b, c); | ||
| } |
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