[llvm-bugs] [Bug 32540] New: Compiler generating extra debug location for btver2 target

[via llvm-bugs]

http://bugs.llvm.org/show_bug.cgi?id=32540

            Bug ID: 32540
           Summary: Compiler generating extra debug location for btver2
                    target
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: douglas_yung at playstation.sony.com
                CC: llvm-bugs at lists.llvm.org

The compiler seems to be generating an extra debug location when compiling the
following code for the btver2 target. Consider the following code:

struct alpha {
  long bravo;
  long charlie;
};
extern int delta(int, unsigned int, unsigned long, double);
extern int echo(struct alpha *);

void foxtrot()
{
        unsigned int gulf = 100;
        struct alpha india, juliet;
  unsigned long hotel = 1;

        echo(&india);
        echo(&juliet);

        double kilo = (((double)juliet.bravo +
((double)juliet.charlie/1000000.0)) - ((double)india.bravo +
((double)india.charlie/1000000.0))); // Line 17
        delta(0, gulf, hotel, (1.0 / (1024.0 *
1024.0))*(double)gulf*(double)hotel/kilo); // Line 18
}

If you compile it to assembly using the command "clang -cc1 -triple
x86_64-unknown-linux-gnu -S -masm-verbose -target-cpu btver2
-debug-info-kind=limited -O0 repro.c", it generates the following assembly for
lines 17 and 18:

        .loc    1 17 0                  # repro.c:17:0
                                        # implicit-def: %XMM0
        vcvtsi2sdq      32(%rsp), %xmm0, %xmm0
                                        # implicit-def: %XMM1
        vcvtsi2sdq      40(%rsp), %xmm1, %xmm1
        vmovsd  .LCPI0_0(%rip), %xmm2   # xmm2 = mem[0],zero
        vdivsd  %xmm2, %xmm1, %xmm1
        vaddsd  %xmm1, %xmm0, %xmm0
                                        # implicit-def: %XMM1
        vcvtsi2sdq      48(%rsp), %xmm1, %xmm1
                                        # implicit-def: %XMM3
        vcvtsi2sdq      56(%rsp), %xmm3, %xmm3
        vdivsd  %xmm2, %xmm3, %xmm2
        vaddsd  %xmm2, %xmm1, %xmm1
        vsubsd  %xmm1, %xmm0, %xmm0
        vmovsd  %xmm0, 16(%rsp)
        .loc    1 18 0                  # repro.c:18:0
        movl    68(%rsp), %ecx
        movl    %ecx, %edi
        movl    %edi, %ecx
        movq    24(%rsp), %rdx
        .loc    1 17 0                  # repro.c:17:0
                                        # implicit-def: %XMM0
        .loc    1 18 0                  # repro.c:18:0
        vcvtsi2sdq      %rdi, %xmm0, %xmm0
        vmovsd  .LCPI0_1(%rip), %xmm1   # xmm1 = mem[0],zero
        vmulsd  %xmm1, %xmm0, %xmm0
        vmovq   %rdx, %xmm1
        vmovdqa .LCPI0_2(%rip), %xmm2   # xmm2 = [1127219200,1160773632,0,0]
        vpunpckldq      %xmm2, %xmm1, %xmm1 # xmm1 =
xmm1[0],xmm2[0],xmm1[1],xmm2[1]
        vmovapd .LCPI0_3(%rip), %xmm2   # xmm2 = [4.503600e+15,1.934281e+25]
        vsubpd  %xmm2, %xmm1, %xmm1
        vhaddpd %xmm1, %xmm1, %xmm1
        vmulsd  %xmm1, %xmm0, %xmm0
        vdivsd  16(%rsp), %xmm0, %xmm0
        movl    12(%rsp), %edi          # 4-byte Reload
        movl    %ecx, %esi
        movl    %eax, 4(%rsp)           # 4-byte Spill
        callq   delta at PLT

Note that it contains an extra debug location for line 17 of repro.c between
two debug locations for line 18. For comparison, if you build the same source,
but do not specify the btver2 target, the following assembly is generated
instead:

        .loc    1 17 0                  # repro.c:17:0
        cvtsi2sdq       32(%rsp), %xmm0
        cvtsi2sdq       40(%rsp), %xmm1
        movsd   .LCPI0_0(%rip), %xmm2   # xmm2 = mem[0],zero
        divsd   %xmm2, %xmm1
        addsd   %xmm1, %xmm0
        cvtsi2sdq       48(%rsp), %xmm1
        cvtsi2sdq       56(%rsp), %xmm3
        divsd   %xmm2, %xmm3
        addsd   %xmm3, %xmm1
        subsd   %xmm1, %xmm0
        movsd   %xmm0, 16(%rsp)
        .loc    1 18 0                  # repro.c:18:0
        movl    68(%rsp), %ecx
        movl    %ecx, %edi
        movl    %edi, %ecx
        movq    24(%rsp), %rdx
        cvtsi2sdq       %rdi, %xmm0
        movsd   .LCPI0_1(%rip), %xmm1   # xmm1 = mem[0],zero
        mulsd   %xmm1, %xmm0
        movd    %rdx, %xmm1
        movaps  .LCPI0_2(%rip), %xmm2   # xmm2 = [1127219200,1160773632,0,0]
        punpckldq       %xmm2, %xmm1    # xmm1 =
xmm1[0],xmm2[0],xmm1[1],xmm2[1]
        movapd  .LCPI0_3(%rip), %xmm2   # xmm2 = [4.503600e+15,1.934281e+25]
        subpd   %xmm2, %xmm1
        pshufd  $78, %xmm1, %xmm2       # xmm2 = xmm1[2,3,0,1]
        addpd   %xmm1, %xmm2
        mulsd   %xmm2, %xmm0
        divsd   16(%rsp), %xmm0
        movl    12(%rsp), %edi          # 4-byte Reload
        movl    %ecx, %esi
        movl    %eax, 4(%rsp)           # 4-byte Spill
        callq   delta at PLT

This does not contain the additional debug location list.

These examples were generated using a compiler built from r299417.

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