[rust/coverage] Pass -z,nostart-stop-gc to the linker
Bug: http://b/199203503
Upstream LLVM change 6d2d3bd0a6 made -z,start-stop-gc the default. It
drops metadata sections like __llvm_prf_data unless they are marked
SHF_GNU_RETAIN. https://reviews.llvm.org/D97448 marks generated
sections, including __llvm_prf_data as SHF_GNU_RETAIN. However this
change is not in the Rust toolchain. Since we link Rust libs with new
lld, we should use nostart-stop-gc until the Rust toolchain updates past
D97448.
Test: m unicode-xid_device_test_src_lib and verify that they have the
__llvm_prf_data section.
Change-Id: I55eb3622dae9bd789fbacfe708600316102c365f
diff --git a/rust/coverage.go b/rust/coverage.go
index 050b811..8fdfa23 100644
--- a/rust/coverage.go
+++ b/rust/coverage.go
@@ -57,7 +57,18 @@
flags.RustFlags = append(flags.RustFlags,
"-Z instrument-coverage", "-g")
flags.LinkFlags = append(flags.LinkFlags,
- profileInstrFlag, "-g", coverage.OutputFile().Path().String(), "-Wl,--wrap,open")
+ profileInstrFlag, "-g", coverage.OutputFile().Path().String(), "-Wl,--wrap,open",
+ // Upstream LLVM change 6d2d3bd0a6 made
+ // -z,start-stop-gc the default. It drops metadata
+ // sections like __llvm_prf_data unless they are marked
+ // SHF_GNU_RETAIN. https://reviews.llvm.org/D97448
+ // marks generated sections, including __llvm_prf_data
+ // as SHF_GNU_RETAIN. However this change is not in
+ // the Rust toolchain. Since we link Rust libs with
+ // new lld, we should use nostart-stop-gc until the
+ // Rust toolchain updates past D97448.
+ "-Wl,-z,nostart-stop-gc",
+ )
deps.StaticLibs = append(deps.StaticLibs, coverage.OutputFile().Path())
}