[llvm-dev] [llvm-bugs] [Bug 38714] [DebugInfo] [DWARF] [AArch64] .debug_loc entry missing in optimized build on aarch64

[Victor Leschuk via llvm-dev]

Including Paul and llvm-dev.

On 8/27/18 12:31 PM, Victor Leschuk wrote:
>
> David, Adrian, could you please advise on this one?
>
> On 8/27/18 12:24 PM, via llvm-bugs wrote:
>> Bug ID 	38714 <https://bugs.llvm.org/show_bug.cgi?id=38714>
>> Summary 	[DebugInfo] [DWARF] [AArch64] .debug_loc entry missing in 
>> optimized build on aarch64
>> Product 	new-bugs
>> Version 	trunk
>> Hardware 	PC
>> OS 	Linux
>> Status 	NEW
>> Severity 	normal
>> Priority 	P
>> Component 	new bugs
>> Assignee 	unassignedbugs at nondot.org
>> Reporter 	vleschuk at accesssoftek.com
>> CC 	llvm-bugs at lists.llvm.org
>>
>> Createdattachment 20771 <attachment.cgi?id=20771> [details] 
>> <attachment.cgi?id=20771&action=edit>
>> Source, object file and generated assembly.
>>
>> When compiling the following sample with optimizations enabled (-O1 and higher)
>> it looks like a .debug_loc entry is missing for argc:
>>
>> #include <stdio.h>
>>
>> int main( int argc, char **argv )
>> {
>>    for(int i = 1; i < argc; ++i) {
>>      printf("Argument %d: %s\n", i, argv[i]);
>>    }
>>    return 0;
>> }
>>
>> $ clang -target aarch64-unknown-linux -c -g -O1 -o test.o test.c
>>
>> There are the following entries:
>>
>> 0x00000043:     DW_TAG_formal_parameter [3]
>>                    DW_AT_location [DW_FORM_sec_offset]   (0x00000000
>>                       [0x0000000000000000,  0x0000000000000034): DW_OP_reg0 W0)
>>                    DW_AT_name [DW_FORM_strp]     ( .debug_str[0x000000d5] =
>> "argc")
>>
>> 0x00000052:     DW_TAG_formal_parameter [3]
>>                    DW_AT_location [DW_FORM_sec_offset]   (0x00000023
>>                       [0x0000000000000000,  0x0000000000000020): DW_OP_reg1 W1
>>                       [0x0000000000000020,  0x0000000000000048): DW_OP_reg19
>> W19)
>>                    DW_AT_name [DW_FORM_strp]     ( .debug_str[0x000000da] =
>> "argv")
>>
>>
>> The assembly for the code is the following:
>>
>>          //DEBUG_VALUE: main:argc <- $w0
>>          //DEBUG_VALUE: main:argv <- $x1
>> .Ltmp0:
>>          //DEBUG_VALUE: i <- 1
>>          .loc    1 5 3 prologue_end      // test.c:5:3
>>          cmp     w0, #2                  // =2
>>          b.lt    .LBB0_3
>> .Ltmp1:
>> // %bb.1:                               // %for.body.preheader
>>          //DEBUG_VALUE: main:argv <- $x1
>>          //DEBUG_VALUE: main:argc <- $w0
>>          .loc    1 0 3 is_stmt 0         // test.c:0:3
>>          adrp    x21, .L.str
>>          mov     x19, x1
>> .Ltmp2:
>>          //DEBUG_VALUE: main:argv <- $x19
>>          mov     w22, w0
>>
>> It looks like there should be two DW_OP_reg* records for w0 and for w22 for
>> argc.
>>
>> Correct me if I am wrong.
>>
>> PS x86 doesn't seem to have this problem.
>> ------------------------------------------------------------------------
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>>
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>>
>>
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> -- 
> Best Regards,
>
> Victor Leschuk | Software Engineer | Access Softek

-- 
Best Regards,

Victor Leschuk | Software Engineer | Access Softek

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