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Add -C link-dead-code option (to improve kcov code coverage) #31368

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Merged
merged 1 commit into from
Feb 12, 2016
Merged

Add -C link-dead-code option (to improve kcov code coverage) #31368

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2 changes: 2 additions & 0 deletions src/librustc/session/config.rs
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Expand Up @@ -507,6 +507,8 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
"system linker to link outputs with"),
link_args: Option<Vec<String>> = (None, parse_opt_list,
"extra arguments to pass to the linker (space separated)"),
link_dead_code: bool = (false, parse_bool,
"let the linker strip dead coded (turning it on can be used for code coverage)"),
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this description is not right, seems it should be "let the linker link dead code" or simply "link dead code"

lto: bool = (false, parse_bool,
"perform LLVM link-time optimizations"),
target_cpu: Option<String> = (None, parse_opt_string,
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4 changes: 3 additions & 1 deletion src/librustc_trans/back/link.rs
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Expand Up @@ -976,7 +976,9 @@ fn link_args(cmd: &mut Linker,

// Try to strip as much out of the generated object by removing unused
// sections if possible. See more comments in linker.rs
cmd.gc_sections(dylib);
if !sess.opts.cg.link_dead_code {
cmd.gc_sections(dylib);
}

let used_link_args = sess.cstore.used_link_args();

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7 changes: 7 additions & 0 deletions src/test/run-make/codegen-options-parsing/Makefile
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Expand Up @@ -22,3 +22,10 @@ all:
$(RUSTC) -C lto=foo dummy.rs 2>&1 | \
grep 'codegen option `lto` takes no value'
$(RUSTC) -C lto dummy.rs

# Should not link dead code...
$(RUSTC) -Z print-link-args dummy.rs 2>&1 | \
grep -e '--gc-sections\|-dead_strip\|/OPT:REF,ICF'
# ... unless you specifically ask to keep it
$(RUSTC) -Z print-link-args -C link-dead-code dummy.rs 2>&1 | \
(! grep -e '--gc-sections\|-dead_strip\|/OPT:REF,ICF')