annotate clang/test/CodeGen/2008-01-25-ByValReadNone.c @ 207:2e18cbf3894f

LLVM12
author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Tue, 08 Jun 2021 06:07:14 +0900
parents 1d019706d866
children
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1 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
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2
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3 // It could hit in @llvm.memcpy with "-triple x86_64-(mingw32|win32)".
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4 // CHECK-NOT: readonly
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5 // CHECK-NOT: readnone
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6
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7 // The struct being passed byval means that we cannot mark the
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8 // function readnone. Readnone would allow stores to the arg to
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9 // be deleted in the caller. We also don't allow readonly since
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10 // the callee might write to the byval parameter. The inliner
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11 // would have to assume the worse and introduce an explicit
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12 // temporary when inlining such a function, which is costly for
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13 // the common case in which the byval argument is not written.
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14 struct S { int A[1000]; };
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15 int __attribute__ ((const)) f(struct S x) { x.A[1] = 0; return x.A[0]; }
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16 int g(struct S x) __attribute__ ((pure));
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17 int h(struct S x) { return g(x); }