File: 2008-01-25-ByValReadNone.c

package info (click to toggle)
llvm-toolchain-7 1%3A7.0.1-8%2Bdeb10u2
  • links: PTS, VCS
  • area: main
  • in suites: buster
  • size: 734,616 kB
  • sloc: cpp: 3,776,926; ansic: 633,271; asm: 350,301; python: 142,716; objc: 107,612; sh: 22,626; lisp: 11,056; perl: 7,999; pascal: 6,742; ml: 5,537; awk: 3,536; makefile: 2,557; cs: 2,027; xml: 841; javascript: 518; ruby: 156
file content (17 lines) | stat: -rw-r--r-- 823 bytes parent folder | download | duplicates (37)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s

// It could hit in @llvm.memcpy with "-triple x86_64-(mingw32|win32)".
// CHECK-NOT: readonly
// CHECK-NOT: readnone

// The struct being passed byval means that we cannot mark the
// function readnone.  Readnone would allow stores to the arg to
// be deleted in the caller.  We also don't allow readonly since
// the callee might write to the byval parameter.  The inliner
// would have to assume the worse and introduce an explicit
// temporary when inlining such a function, which is costly for
// the common case in which the byval argument is not written.
struct S { int A[1000]; };
int __attribute__ ((const)) f(struct S x) { x.A[1] = 0; return x.A[0]; }
int g(struct S x) __attribute__ ((pure));
int h(struct S x) { return g(x); }