CI: Setup cross build test

.github/workflows/cross.yml

@@ -0,0 +1,60 @@
+name: Cross
+
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+    tags: '*'
+
+jobs:
+  build-cross-qemu:
+    runs-on: ubuntu-latest
+    name: build-cross-qemu-${{ matrix.config.arch }}
+    strategy:
+      fail-fast: false
+      matrix:
+        config:
+          - { arch: arm,      triple: arm-linux-gnueabihf }
+          - { arch: aarch64,  triple: aarch64-linux-gnu }
+          - { arch: ppc,      triple: powerpc-linux-gnu }
+          - { arch: ppc64,    triple: powerpc64-linux-gnu }
+          - { arch: ppc64le,  triple: powerpc64le-linux-gnu }
+          - { arch: mips,     triple: mips-linux-gnu }
+          - { arch: mipsel,   triple: mipsel-linux-gnu }
+          # Builds successfully, but tests fail.
+          # - { arch: mips64,   triple: mips64-linux-gnuabi64 }
+          # - { arch: mips64el, triple: mips64el-linux-gnuabi64 }
+          - { arch: riscv64,  triple: riscv64-linux-gnu }
+          - { arch: s390x,    triple: s390x-linux-gnu }
+    env:
+      ARCH: ${{ matrix.config.arch }}
+      TRIPLE: ${{ matrix.config.triple }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install QEMU
+        # this ensure install latest qemu on ubuntu, apt get version is old
+        env:
+          QEMU_SRC: "http://archive.ubuntu.com/ubuntu/pool/universe/q/qemu"
+          QEMU_VER: "qemu-user-static_7\\.2+dfsg-.*_amd64.deb$"
+        run: |
+          DEB=`curl -s $QEMU_SRC/ | grep -o -E 'href="([^"#]+)"' | cut -d'"' -f2 | grep $QEMU_VER | tail -1`
+          wget $QEMU_SRC/$DEB
+          sudo dpkg -i $DEB
+      - name: Install toolchain gcc-${{ matrix.config.triple }}
+        run: |
+          sudo apt update
+          sudo apt install gcc-$TRIPLE -y
+      - name: Build with ${{ matrix.config.triple }}-gcc
+        run: make ARCH=$ARCH TOOLPREFIX=$TRIPLE-
+      - name: Build tests
+        run: make -C test ARCH=$ARCH TOOLPREFIX=$TRIPLE-
+      - name: Run Tests
+        env:
+          QEMU_EXEC: qemu-${{ matrix.config.arch }}-static
+          CROSS_LIB: /usr/${{ matrix.config.triple }}
+        run: |
+          $QEMU_EXEC -L . -L $CROSS_LIB/  test/test-float
+          $QEMU_EXEC -L . -L $CROSS_LIB/  test/test-double

Make.inc

@@ -23,6 +23,7 @@ endif
 
 USEGCC ?= 1
 USECLANG ?= 0
+TOOLPREFIX ?=
 
 ifneq (,$(findstring $(OS),Darwin FreeBSD OpenBSD))
 USEGCC ?= 0
@@ -34,7 +35,7 @@ USECLANG = 1
 TOOLPREFIX = llvm-
 endif
 
-AR ?= $(TOOLPREFIX)ar
+AR := $(TOOLPREFIX)ar
 
 ifeq ($(USECLANG),1)
 USEGCC ?= 0
@@ -43,7 +44,7 @@ CFLAGS_add += -fno-builtin -fno-strict-aliasing
 endif
 
 ifeq ($(USEGCC),1)
-CC ?= $(TOOLPREFIX)gcc
+CC := $(TOOLPREFIX)gcc
 CFLAGS_add += -fno-gnu89-inline -fno-builtin
 endif
 
@@ -59,7 +60,7 @@ override ARCH := aarch64
 endif
 ifeq ($(findstring arm,$(ARCH)),arm)
 override ARCH := arm
-MARCH ?= armv7-a
+MARCH ?= armv7-a+fp
 CFLAGS_add += -mhard-float
 endif
 ifeq ($(findstring powerpc,$(ARCH)),powerpc)

README.md

@@ -33,6 +33,25 @@ loongarch64.
    i686. GCC 4.8 is the minimum requirement for correct codegen on
    older 32-bit architectures.
 
+
+**Cross Build**
+Take `riscv64` as example:
+1. install `qemu-riscv64-static`, `gcc-riscv64-linux-gnu`
+2. Cross build:
+```sh
+ARCH=riscv64
+TRIPLE=$ARCH-linux-gnu
+make ARCH=$ARCH TOOLPREFIX=$TRIPLE-  -j
+make -C test ARCH=$ARCH TOOLPREFIX=$TRIPLE-  -j
+```
+
+3. Run test with qemu:
+```sh
+qemu-$ARCH-static -L . -L /usr/$TRIPLE/  test/test-float
+qemu-$ARCH-static -L . -L /usr/$TRIPLE/  test/test-double
+```
+
+
 ### CMake
 
 1. Create build directory with `mkdir build` and navigate into it with `cd build`.