Bug 1481721 - Switch Linux nightlies and PGO builds to clang r=froydnj

And enable LTO on CI builds using clang + PGO.

Differential Revision: https://phabricator.services.mozilla.com/D4991

--HG--
extra : moz-landing-system : lando

build/mozconfig.no-compile

@@ -21,6 +21,7 @@ unset MAKECAB
 unset TOOLCHAIN_PREFIX
 unset BINDGEN_CFLAGS
 unset LLVM_CONFIG
+unset LLVM_PROFDATA
 unset WIN64_LINK
 unset WIN64_LIB
 unset ENABLE_CLANG_PLUGIN

build/unix/mozconfig.unix

@@ -7,7 +7,7 @@ fi
 
 TOOLTOOL_DIR=${TOOLTOOL_DIR:-$topsrcdir}
 
-if [ -n "$FORCE_GCC" -o -n "$MOZ_PGO" ]; then
+if [ -n "$FORCE_GCC" ]; then
     CC="$TOOLTOOL_DIR/gcc/bin/gcc"
     CXX="$TOOLTOOL_DIR/gcc/bin/g++"
 
@@ -19,6 +19,14 @@ else
     CXX="$TOOLTOOL_DIR/clang/bin/clang++"
     export ENABLE_CLANG_PLUGIN=1
 
+    if [ -n "$MOZ_PGO" ]; then
+        ac_add_options --enable-lto
+        export LLVM_PROFDATA="$TOOLTOOL_DIR/clang/bin/llvm-profdata"
+        export AR="$topsrcdir/clang/bin/llvm-ar"
+        export NM="$topsrcdir/clang/bin/llvm-nm"
+        export RANLIB="$topsrcdir/clang/bin/llvm-ranlib"
+    fi
+
     mk_add_options "export PATH=$TOOLTOOL_DIR/binutils/bin:$PATH"
 fi
 

taskcluster/ci/build/linux.yml

@@ -24,7 +24,6 @@ linux64/opt:
     toolchains:
         - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -108,8 +107,6 @@ linux64/pgo:
     worker-type: aws-provisioner-v1/gecko-{level}-b-linux
     worker:
         max-run-time: 7200
-        env:
-            FORCE_GCC: '1'
     run:
         using: mozharness
         actions: [get-secrets build check-test update]
@@ -122,8 +119,8 @@ linux64/pgo:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
+        - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -244,8 +241,6 @@ linux64-devedition-nightly/opt:
     worker-type: aws-provisioner-v1/gecko-{level}-b-linux
     worker:
         max-run-time: 7200
-        env:
-            FORCE_GCC: '1'
     run:
         using: mozharness
         actions: [get-secrets build check-test update]
@@ -260,8 +255,8 @@ linux64-devedition-nightly/opt:
         custom-build-variant-cfg: devedition
     run-on-projects: ['mozilla-beta']
     toolchains:
+        - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -360,7 +355,6 @@ linux/opt:
     toolchains:
         - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -415,8 +409,6 @@ linux/pgo:
     worker:
         docker-image: {in-tree: debian7-i386-build}
         max-run-time: 7200
-        env:
-            FORCE_GCC: '1'
     run:
         using: mozharness
         actions: [get-secrets build check-test update]
@@ -429,8 +421,8 @@ linux/pgo:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
+        - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -527,8 +519,6 @@ linux-devedition-nightly/opt:
     worker:
         docker-image: {in-tree: debian7-i386-build}
         max-run-time: 7200
-        env:
-            FORCE_GCC: '1'
     run:
         using: mozharness
         actions: [get-secrets build check-test update]
@@ -543,8 +533,8 @@ linux-devedition-nightly/opt:
         custom-build-variant-cfg: devedition
     run-on-projects: ['mozilla-beta']
     toolchains:
+        - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -569,8 +559,6 @@ linux-nightly/opt:
     worker:
         docker-image: {in-tree: debian7-i386-build}
         max-run-time: 7200
-        env:
-            FORCE_GCC: '1'
     run:
         using: mozharness
         actions: [get-secrets build check-test update]
@@ -583,8 +571,8 @@ linux-nightly/opt:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
+        - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen
@@ -883,8 +871,6 @@ linux64-nightly/opt:
     worker-type: aws-provisioner-v1/gecko-{level}-b-linux
     worker:
         max-run-time: 7200
-        env:
-            FORCE_GCC: '1'
     run:
         using: mozharness
         actions: [get-secrets build check-test update]
@@ -897,8 +883,8 @@ linux64-nightly/opt:
         tooltool-downloads: public
         need-xvfb: true
     toolchains:
+        - linux64-binutils
         - linux64-clang
-        - linux64-gcc
         - linux64-rust
         - linux64-rust-size
         - linux64-cbindgen