[Coverage][WebAssembly] Add initial support for WebAssembly/WASI (#111332)

Currently, WebAssembly/WASI target does not provide direct support for
code coverage.
This patch set fixes several issues to unlock the feature. The main
changes are:

1. Port `compiler-rt/lib/profile` to WebAssembly/WASI.
2. Adjust profile metadata sections for Wasm object file format.
- [CodeGen] Emit `__llvm_covmap` and `__llvm_covfun` as custom sections
instead of data segments.
    - [lld] Align the interval space of custom sections at link time.
- [llvm-cov] Copy misaligned custom section data if the start address is
not aligned.
    - [llvm-cov] Read `__llvm_prf_names` from data segments
3. [clang] Link with profile runtime libraries if requested

See each commit message for more details and rationale.
This is part of the effort to add code coverage support in Wasm target
of Swift toolchain.

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 0d3e4ba..ce50a3c 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -2171,7 +2171,11 @@ MCSection *TargetLoweringObjectFileWasm::getExplicitSectionGlobal(
   // This could be avoided if all data segements (the wasm sense) were
   // represented as their own sections (in the llvm sense).
   // TODO(sbc): https://github.com/WebAssembly/tool-conventions/issues/138
-  if (Name == ".llvmcmd" || Name == ".llvmbc")
+  if (Name == getInstrProfSectionName(IPSK_covmap, Triple::Wasm,
+                                      /*AddSegmentInfo=*/false) ||
+      Name == getInstrProfSectionName(IPSK_covfun, Triple::Wasm,
+                                      /*AddSegmentInfo=*/false) ||
+      Name == ".llvmbc" || Name == ".llvmcmd")
     Kind = SectionKind::getMetadata();
 
   StringRef Group = "";