all: add support for LLVM 20

This adds support for the 'go install' case, where we link against the
system LLVM (Homebrew, Linux distro version, etc). This does not have an
effect on `make`, which still uses LLVM 19 for now.

The main reason for doing this is because newer distros like Fedora 42
and Homebrew have switched to LLVM 20, so switching to this newer
version helps those people. (I'm one of those people, I'm on Fedora 42).

There are two small changes for WebAssembly included:

  * nontrapping-fptoint was enabled in the wasmbuiltin library used for
    wasm-unknown. This matches wasm-unknown which already had this
    enabled, so it doesn't add any new instructions.
  * bulk-memory was enabled in wasi-libc. This was previously enabled in
    all the other WebAssembly targets (wasm, wasip1, wasip2) so this
    does't add any new instructions. I think it was also enabled in the
    wasi-libc build before
    #4820 but I don't know for
    sure.

Author: aykevl

.circleci/config.yml

@@ -101,12 +101,12 @@ jobs:
           # "make lint" fails before go 1.21 because internal/tools/go.mod specifies packages that require go 1.21
           fmt-check: false
     resource_class: large
-  test-llvm19-go124:
+  test-llvm20-go124:
     docker:
       - image: golang:1.24-bullseye
     steps:
       - test-linux:
-          llvm: "19"
+          llvm: "20"
     resource_class: large
 
 workflows:
@@ -115,5 +115,5 @@ workflows:
       # This tests our lowest supported versions of Go and LLVM, to make sure at
       # least the smoke tests still pass.
       - test-llvm15-go119
-      # This tests LLVM 19 support when linking against system libraries.
-      - test-llvm19-go124
+      # This tests LLVM 20 support when linking against system libraries.
+      - test-llvm20-go124

.github/workflows/build-macos.yml

@@ -117,7 +117,7 @@ jobs:
     runs-on: macos-latest
     strategy:
       matrix:
-        version: [16, 17, 18, 19]
+        version: [16, 17, 18, 19, 20]
     steps:
       - name: Set up Homebrew
         uses: Homebrew/actions/setup-homebrew@master
@@ -141,8 +141,8 @@ jobs:
       - name: Check binary
         run: tinygo version
       - name: Build TinyGo (default LLVM)
-        if: matrix.version == 19
+        if: matrix.version == 20
         run: go install
       - name: Check binary
-        if: matrix.version == 19
+        if: matrix.version == 20
         run: tinygo version

.github/workflows/sizediff-install-pkgs.sh

@@ -2,11 +2,11 @@
 # still works after checking out the dev branch (that is, when going from LLVM
 # 16 to LLVM 17 for example, both Clang 16 and Clang 17 are installed).
 
-echo 'deb https://apt.llvm.org/noble/ llvm-toolchain-noble-19 main' | sudo tee /etc/apt/sources.list.d/llvm.list
+echo 'deb https://apt.llvm.org/noble/ llvm-toolchain-noble-20 main' | sudo tee /etc/apt/sources.list.d/llvm.list
 wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
 sudo apt-get update
 sudo apt-get install --no-install-recommends -y \
-    llvm-19-dev \
-    clang-19 \
-    libclang-19-dev \
-    lld-19
+    llvm-20-dev \
+    clang-20 \
+    libclang-20-dev \
+    lld-20

builder/wasilibc.go

@@ -93,12 +93,13 @@ var libWasiLibc = Library{
 			"-Wall",
 			"-std=gnu11",
 			"-nostdlibinc",
-			"-mnontrapping-fptoint", "-msign-ext",
+			"-mnontrapping-fptoint", "-msign-ext", "-mbulk-memory",
 			"-Wno-null-pointer-arithmetic", "-Wno-unused-parameter", "-Wno-sign-compare", "-Wno-unused-variable", "-Wno-unused-function", "-Wno-ignored-attributes", "-Wno-missing-braces", "-Wno-ignored-pragmas", "-Wno-unused-but-set-variable", "-Wno-unknown-warning-option",
 			"-Wno-parentheses", "-Wno-shift-op-parentheses", "-Wno-bitwise-op-parentheses", "-Wno-logical-op-parentheses", "-Wno-string-plus-int", "-Wno-dangling-else", "-Wno-unknown-pragmas",
 			"-DNDEBUG",
 			"-D__wasilibc_printscan_no_long_double",
 			"-D__wasilibc_printscan_full_support_option=\"long double support is disabled\"",
+			"-DBULK_MEMORY_THRESHOLD=32", // default threshold in wasi-libc
 			"-isystem", headerPath,
 			"-I" + libcDir + "/libc-top-half/musl/src/include",
 			"-I" + libcDir + "/libc-top-half/musl/src/internal",

builder/wasmbuiltins.go

@@ -29,6 +29,8 @@ var libWasmBuiltins = Library{
 			"-Wall",
 			"-std=gnu11",
 			"-nostdlibinc",
+			"-mnontrapping-fptoint", // match wasm-unknown (default on in LLVM 20)
+			"-mno-bulk-memory",      // same here
 			"-isystem", libcDir + "/libc-top-half/musl/arch/wasm32",
 			"-isystem", libcDir + "/libc-top-half/musl/arch/generic",
 			"-isystem", libcDir + "/libc-top-half/musl/src/internal",

cgo/libclang_config_llvm19.go

@@ -1,4 +1,4 @@
-//go:build !byollvm && !llvm15 && !llvm16 && !llvm17 && !llvm18
+//go:build !byollvm && llvm19
 
 package cgo
 

cgo/libclang_config_llvm20.go

@@ -0,0 +1,15 @@
+//go:build !byollvm && !llvm15 && !llvm16 && !llvm17 && !llvm18 && !llvm19
+
+package cgo
+
+/*
+#cgo linux        CFLAGS:  -I/usr/include/llvm-20 -I/usr/include/llvm-c-20 -I/usr/lib/llvm-20/include
+#cgo darwin,amd64 CFLAGS:  -I/usr/local/opt/llvm@20/include
+#cgo darwin,arm64 CFLAGS:  -I/opt/homebrew/opt/llvm@20/include
+#cgo freebsd      CFLAGS:  -I/usr/local/llvm20/include
+#cgo linux        LDFLAGS: -L/usr/lib/llvm-20/lib -lclang
+#cgo darwin,amd64 LDFLAGS: -L/usr/local/opt/llvm@20/lib -lclang
+#cgo darwin,arm64 LDFLAGS: -L/opt/homebrew/opt/llvm@20/lib -lclang
+#cgo freebsd      LDFLAGS: -L/usr/local/llvm20/lib -lclang
+*/
+import "C"

go.mod

@@ -20,7 +20,7 @@ require (
 	golang.org/x/sys v0.21.0
 	golang.org/x/tools v0.22.1-0.20240621165957-db513b091504
 	gopkg.in/yaml.v2 v2.4.0
-	tinygo.org/x/go-llvm v0.0.0-20250119132755-9dca92dfb4f9
+	tinygo.org/x/go-llvm v0.0.0-20250422114502-b8f170971e74
 )
 
 require (

go.sum

@@ -74,5 +74,5 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-tinygo.org/x/go-llvm v0.0.0-20250119132755-9dca92dfb4f9 h1:rMvEzuCYjyiR+pmdiCVWTQw3L6VqiSIXoL19I3lYufE=
-tinygo.org/x/go-llvm v0.0.0-20250119132755-9dca92dfb4f9/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=
+tinygo.org/x/go-llvm v0.0.0-20250422114502-b8f170971e74 h1:ovavgTdIBWCH8YWlcfq9gkpoyT1+IxMKSn+Df27QwE8=
+tinygo.org/x/go-llvm v0.0.0-20250422114502-b8f170971e74/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=