[llvm-bugs] [Bug 46586] New: Clang produces wrong code with -O1 (Combine redundant instructions on function)

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=46586

            Bug ID: 46586
           Summary: Clang produces wrong code with -O1 (Combine redundant
                    instructions on function)
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: Vsevolod.Livinskij at frtk.ru
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

>$ clang++ -O1 func.cpp driver.cpp && ./a.out 
277562856
>$ clang++ -O0 func.cpp driver.cpp && ./a.out 
0
Reproducer:

//func.cpp
extern int var_22;
void test(unsigned a, unsigned short b, unsigned short c, signed char d,
          short e, unsigned char f, long long g,
          unsigned char h[2][20][22][21][15]) {
  for (bool i = 0; i < 1; i = f)
    for (char j = 0; j < 9; j = 75)
      for (bool k = 0; k < (bool)d /*1*/; k = 1)
        for (int l = 0; l < c /*45282*/; l = g /*1453005525*/)
#pragma clang loop interleave(enable)
          for (int m = 0; m < e + 31262 /*14*/; m += b - 55386 /*4*/)
            var_22 = h[i][j][7][l][m] % a;
}

//driver.cpp 
#include <stdio.h>

unsigned int var_0 = 1369684504U;
unsigned short var_2 = (unsigned short)55390;
unsigned short var_3 = (unsigned short)45282;
signed char var_4 = (signed char)115;
short var_5 = (short)-31248;
unsigned char var_7 = (unsigned char)161;
long long int var_9 = 7910119181202954965LL;
unsigned int var_22 = 3518480962U;
unsigned char arr_11 [2] [20] [22] [21] [15] ;

void test(unsigned int var_0, unsigned short var_2, unsigned short var_3,
signed char var_4, short var_5, unsigned char var_7, long long int var_9,
unsigned char arr_11 [2] [20] [22] [21] [15]);

int main() {
    test(var_0, var_2, var_3, var_4, var_5, var_7, var_9, arr_11);
    printf("%u\n", var_22);
}

Clang version:
clang version 11.0.0 (https://github.com/llvm/llvm-project.git
120c5f1057dc50229f73bc75bbabf4df6ee50fef)

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20200704/2d773c0f/attachment.html>