Commit cf8753e

maurerrcvalle

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Make lto and linker-plugin-lto work the same for compiler_builtins

Fix #142284 by ensuring that `#![no_builtins]` crates can still emit bitcode when proper (i.e., non-rustc) LTO (i.e., -Clinker-plugin-lto) is used.

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+23

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+23

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Lines changed: 1 addition & 12 deletions

Original file line number	Diff line number	Diff line change
`@@ -143,23 +143,12 @@ impl ModuleConfig {`
`143`	`143`
`144`	`144`	`let emit_obj = if !should_emit_obj {`
`145`	`145`	`EmitObj::None`
`146`		`- } else if sess.target.obj_is_bitcode`
`147`		`- \|\| (sess.opts.cg.linker_plugin_lto.enabled() && !no_builtins)`
`148`		`- {`
	`146`	`+ } else if sess.target.obj_is_bitcode \|\| sess.opts.cg.linker_plugin_lto.enabled() {`
`149`	`147`	`// This case is selected if the target uses objects as bitcode, or`
`150`	`148`	`// if linker plugin LTO is enabled. In the linker plugin LTO case`
`151`	`149`	`// the assumption is that the final link-step will read the bitcode`
`152`	`150`	`// and convert it to object code. This may be done by either the`
`153`	`151`	`// native linker or rustc itself.`
`154`		`- //`
`155`		`- // Note, however, that the linker-plugin-lto requested here is`
`156`		- // explicitly ignored for `#![no_builtins]` crates. These crates are
`157`		`- // specifically ignored by rustc's LTO passes and wouldn't work if`
`158`		`- // loaded into the linker. These crates define symbols that LLVM`
`159`		`- // lowers intrinsics to, and these symbol dependencies aren't known`
`160`		`- // until after codegen. As a result any crate marked`
`161`		- // `#![no_builtins]` is assumed to not participate in LTO and
`162`		`- // instead goes on to generate object code.`
`163`	`152`	`EmitObj::Bitcode`
`164`	`153`	`} else if need_bitcode_in_object(tcx) {`
`165`	`154`	`EmitObj::ObjectCode(BitcodeSection::Full)`

Lines changed: 22 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,22 @@`
	`1`	+// Verifies that `#![no_builtins]` crates can be built with linker-plugin-lto and CFI.
	`2`	`+// See Issue #142284`
	`3`	`+//`
	`4`	`+//@ needs-sanitizer-cfi`
	`5`	`+//@ compile-flags: -Clinker-plugin-lto -Copt-level=0 -Zsanitizer=cfi -Ctarget-feature=-crt-static`
	`6`	`+//@ compile-flags: --crate-type rlib`
	`7`	`+//@ build-pass`
	`8`	`+`
	`9`	`+#![no_builtins]`
	`10`	`+#![no_std]`
	`11`	`+`
	`12`	`+pub static FUNC: fn() = initializer;`
	`13`	`+`
	`14`	`+pub fn initializer() {`
	`15`	`+ call(fma_with_fma);`
	`16`	`+}`
	`17`	`+`
	`18`	`+pub fn call(fn_ptr: fn()) {`
	`19`	`+ fn_ptr();`
	`20`	`+}`
	`21`	`+`
	`22`	`+pub fn fma_with_fma() {}`

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