条件跳转或移动取决于函数调用中未初始化的值
Conditional jump or move depends on uninitialised value(s) on function call
我已经处理这个问题一段时间了，我不明白为什么它不起作用。该代码只是用于解决模拟问题的工作程序的扩展。我刚刚在结构中添加了两个字符串变量，还调整了必要的函数，以便移交额外的参数。Valgrind显示大约20种不同的条件跳跃或移动取决于未初始化的值错误。所有这些都提供了相同的错误信息：
Uninitialised value was created by a stack allocation
at 0x401E23: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:360)
以下是各自的功能：
typedef struct tproxel *pproxel;
typedef struct tproxel {
int id; /* unique proxel id for searching */
int s; /* discrete state of SPN */
int tau1k; /* first supplementary variable */
int tau2k; /* second supplementary variable */
double val; /* proxel probability */
string path; /* previous path */
string output; /* previous output */
pproxel left, right; /* pointers to child proxels in tree */
} proxel;
/* adds a new proxel to the tree */
void addproxel(int s, int tau1k, int tau2k, double val, string &path, string &output) {
proxel *temp, *temp2;
int cont = 1,id;
/* Alarm! TAUMAX overstepped! */
if (tau1k >= TAUMAX) {
// printf(">>> %3d %3d %3d %7.5le n", s, tau1k, val, TAUMAX);
tau1k = TAUMAX - 1;
}
/* compute id of new proxel */
id = TAUMAX*(TAUMAX*s+tau1k)+tau2k;
/* New tree, add root */
if (root[sw] == NULL) {
root[sw] = insertproxel(s,tau1k, tau2k, val, path, output);
root[sw]->left = NULL;
root[sw]->right = NULL;
return;
}
/* Locate insertion point in tree */
temp = root[sw];
while (cont == 1) {
if ((temp->left != NULL) && (id < temp->id))
temp = temp->left;
else
if ((temp->right != NULL) && (id > temp->id))
temp = temp->right;
else
cont = 0;
}
/* Insert left leaf into tree */
if ((temp->left == NULL) && (id < temp->id)) {
temp2 = insertproxel(s, tau1k,tau2k, val, path, output);
temp->left = temp2;
temp2->left = NULL;
temp2->right = NULL;
return;
}
/* Insert right leaf into tree */
if ((temp->right == NULL) && (id > temp->id)) {
temp2 = insertproxel(s, tau1k,tau2k, val, path, output);
temp->right = temp2;
temp2->left = NULL;
temp2->right = NULL;
return;
}
/* Proxels have the same id, just add their vals */
if (id == temp->id) {
temp->val += val;
return;
}
printf("nnn!!!!!! addproxel failed !!!!!nnn");
}
/* compute size of tree */
int size(proxel *p) {
int sl, sr;
if (p == NULL)
return(0);
sl = size(p->left);
sr = size(p->right);
return(sl+sr+1);
}
在添加两个字符串变量之前，代码运行得很好，但现在我只遇到了内存访问冲突。经过几个小时的努力，我不知道可能出了什么问题。
我希望有人能告诉我我错过了什么，任何帮助都将不胜感激。
编辑：
我已经把@Jens指出的内容改回了原始程序中的工作代码，现在我得到了不同的错误：
==1900== 1 errors in context 1 of 4:
==1900== Invalid read of size 4
==1900== at 0x5159218: std::string::assign(std::string const&) (in /usr/lib/libstdc++.so.6.0.13)
==1900== by 0x401CF1: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:347)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
==1900== Address 0xfffffffffffffff8 is not stack'd, malloc'd or (recently) free'd
==1900==
==1900==
==1900== 1 errors in context 2 of 4:
==1900== Use of uninitialised value of size 8
==1900== at 0x5159218: std::string::assign(std::string const&) (in /usr/lib/libstdc++.so.6.0.13)
==1900== by 0x401CF1: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:347)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
==1900== Uninitialised value was created by a heap allocation
==1900== at 0x4C274A8: malloc (vg_replace_malloc.c:236)
==1900== by 0x401C57: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:336)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
==1900==
==1900==
==1900== 1 errors in context 3 of 4:
==1900== Conditional jump or move depends on uninitialised value(s)
==1900== at 0x51591A5: std::string::assign(std::string const&) (in /usr/lib/libstdc++.so.6.0.13)
==1900== by 0x401CF1: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:347)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
==1900== Uninitialised value was created by a heap allocation
==1900== at 0x4C274A8: malloc (vg_replace_malloc.c:236)
==1900== by 0x401C57: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:336)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
==1900==
==1900==
==1900== 1 errors in context 4 of 4:
==1900== Conditional jump or move depends on uninitialised value(s)
==1900== at 0x5159181: std::string::assign(std::string const&) (in /usr/lib/libstdc++.so.6.0.13)
==1900== by 0x401CF1: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:347)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
==1900== Uninitialised value was created by a heap allocation
==1900== at 0x4C274A8: malloc (vg_replace_malloc.c:236)
==1900== by 0x401C57: insertproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:336)
==1900== by 0x401E48: addproxel(int, int, int, double, std::string&, std::string&) (HNMM.cpp:374)
==1900== by 0x402195: main (HNMM.cpp:465)
相应的代码和错误产生行：
/* get a fresh proxel and copy data into it */
proxel *insertproxel(int s, int tau1k, int tau2k, double val, string &path, string &output) {
proxel *temp;
/* create new proxel or grab one from free list */
if (firstfree == NULL)
temp = (proxel*) malloc(sizeof(proxel));
else {
temp = firstfree;
firstfree = firstfree->right;
}
/* copy values */
temp->id = TAUMAX*(TAUMAX*s+tau1k)+tau2k;
temp->s = s;
temp->tau1k = tau1k;
temp->tau2k = tau2k;
temp->val = val;
temp->path = string(path);
temp->output = string(output);
ccpcnt += 1;
if (maxccp < ccpcnt) {
maxccp = ccpcnt;
//printf("n ccpcnt=%d",ccpcnt);
}
return(temp);
}
第336行：
temp = (proxel*) malloc(sizeof(proxel));
347行：
temp->path = string(path);
第374行：
root[sw] = insertproxel(s,tau1k, tau2k, val, path, output);
在insertproxel中，返回对堆栈分配变量的引用：
proxel temp2 = {0};
temp = &temp2;
/* ... */
return(temp);
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