1ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 2ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include <stdio.h> 3ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#include <stdlib.h> 4ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 5ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// Do a test comparison. By default memcheck does not use the 6ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// expensive EQ/NE scheme as it would be too expensive. The 7ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// assignment to *hack is a trick to fool memcheck's bogus-literal 8ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// spotter into thinking this is a bb which needs unusually careful 9ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// attention, and therefore the expensive EQ/NE scheme is used. 10ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 11ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown__attribute__((noinline)) // keep your grubby hands off this fn 12ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownvoid foo ( int* p1, int* p2, unsigned int * hack ) 13ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown{ 14ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown *hack = 0x80808080; 15ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown if (*p1 == *p2) 16ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown printf("foo\n"); 17ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown else 18ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown printf("bar\n"); 19ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown} 20ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 21ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownstatic void bar ( void ); 22ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownint main ( void ) 23ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown{ 24ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 25ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown unsigned int hack; 26ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 27ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown int* junk1 = malloc(sizeof(int)); 28ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown int* junk2 = malloc(sizeof(int)); 29ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 30ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown short* ps1 = (short*)junk1; 31ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown short* ps2 = (short*)junk2; 32ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 33ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown int* pi1 = (int*)junk1; 34ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown int* pi2 = (int*)junk2; 35ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown bar(); 36ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // both words completely undefined. This should give an error. 37ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown foo(pi1,pi2, &hack); 38ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 39ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // set half of the words, but to different values; so this should 40ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // not give an error, since inspection of the defined parts 41ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // shows the two values are not equal, and so the definedness of 42ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // the conclusion is unaffected by the undefined halves. 43ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown *ps1 = 41; 44ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown *ps2 = 42; 45ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown foo(pi1,pi2, &hack); 46ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 47ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // set half of the words, but to the same value, so this forces the 48ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // result of the comparison to depend on the undefined halves. 49ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown // should give an error 50ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown *ps1 = 42; 51ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown *ps2 = 42; 52ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown foo(pi1,pi2, &hack); 53ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 54ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown return 0; 55ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown} 56ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown 57ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// Note: on ppc32/64 the second call to foo() does give an error, 58ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// since the expensive EQ/NE scheme does not apply to the CmpORD 59ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// primops used by ppc. 60ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// 61ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// On arm, the "normal" (x86-like) comparison primops are used, so 62ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// the expensive EQ/NE scheme could apply. However, it doesn't, 63ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// because the constant 0x80808080 is placed in a constant pool 64ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// and so never appears as a literal, and so the instrumenter 65ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// never spots it and so doesn't use the expensive scheme (for foo). 66ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown// Hence also on ARM we get 3 errors, not 2. 67b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov// 68b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov// s390x is even more complicated: Depending on the architecture 69b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov// level we have the 0x80808080 either in the literal pool (3 errors) 70b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov// or with the extended immediate facility in an instruction (2 errors). 71ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brownstatic __attribute__((noinline)) void bar ( void ) 72ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown{ 73ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#if defined(__powerpc__) || defined(__powerpc64__) || defined(__arm__) 74ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown fprintf(stderr, "Currently running on ppc32/64/arm: this test should give 3 errors, not 2.\n"); 75ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown#endif 76b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov#if defined(__s390__) 77b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov fprintf(stderr, "On s390 we might see 2 or 3 errors.\n"); 78b32f58018498ea2225959b0ba11c18f0c433deefEvgeniy Stepanov#endif 79ed07e00d438c74b7a23c01bfffde77e3968305e4Jeff Brown} 80