1973076 - JumpTarget ops have the bad line number information

Status: NEW

(Core :: JavaScript Engine, task)

Description

[Jeff Muizelaar [:jrmuizel]]

Example

function f(x) {
    if (x === 5) {
        return 1;
    }
    return 2;
}

loc   line  op
----- ----  --
main:
00000:   2  GetArg 0                    # x
00003:   2  StrictConstantEq 261        # (x === 5)
00006:   2  JumpIfFalse 18 (+12)        # 
00011:   2  JumpTarget (ic: 1)          # 
00016:   3  One                         # 1
00017:   6  Return                      # 
00018:   6  JumpTarget (ic: 1)          # 
00023:   5  Int8 2                      # 2
00025:   6  Return                      # 
00026:   6  RetRval                     # !!! UNREACHABLE !!!

Most obvious is the JumpTarget at 00018 that has a lineno of 6 when it should obviously be 5

Comment 1

[Nicolas B. Pierron [:nbp]]

There is no source associated with JumpTarget, this is an opcode that I added initially for sanity checks of the stack depth, and later reused for code coverage.

What is the broader issue you are facing, is that the JumpTarget, or something else?

Comment 2

[Jeff Muizelaar [:jrmuizel]]

The bad line number info on JumpTargets causes us to generate bad jit dump source info here: https://searchfox.org/mozilla-central/rev/158fb9063c06a36e6a2efb2b1823bba8c01e82a1/js/src/jit/PerfSpewer.cpp#760