[Xtensa] Initial porting compiler-rt library for Xtensa.

Author: andreisfr

compiler-rt/cmake/Modules/CompilerRTUtils.cmake

@@ -208,6 +208,8 @@ macro(detect_target_arch)
     add_default_target_arch(sparc)
   elseif(__WEBASSEMBLY32)
     add_default_target_arch(wasm32)
+  elseif(__XTENSA)
+    add_default_target_arch(xtensa)
   elseif(__WEBASSEMBLY64)
     add_default_target_arch(wasm64)
   elseif(__VE)

compiler-rt/cmake/base-config-ix.cmake

@@ -237,6 +237,8 @@ macro(test_targets)
       test_target_arch(riscv64 "" "")
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "wasm32")
       test_target_arch(wasm32 "" "--target=wasm32-unknown-unknown")
+    elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "xtensa")
+      test_target_arch(xtensa "" "--target=xtensa")
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "wasm64")
       test_target_arch(wasm64 "" "--target=wasm64-unknown-unknown")
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "ve")

compiler-rt/cmake/builtin-config-ix.cmake

@@ -51,6 +51,7 @@ set(SPARC sparc)
 set(SPARCV9 sparcv9)
 set(WASM32 wasm32)
 set(WASM64 wasm64)
+set(XTENSA xtensa)
 set(VE ve)
 
 if(APPLE)
@@ -63,7 +64,7 @@ set(ALL_BUILTIN_SUPPORTED_ARCH
   ${X86} ${X86_64} ${ARM32} ${ARM64}
   ${HEXAGON} ${MIPS32} ${MIPS64} ${PPC32} ${PPC64}
   ${RISCV32} ${RISCV64} ${SPARC} ${SPARCV9}
-  ${WASM32} ${WASM64} ${VE})
+  ${WASM32} ${WASM64} ${VE} ${XTENSA})
 
 include(CompilerRTUtils)
 include(CompilerRTDarwinUtils)

compiler-rt/lib/builtins/CMakeLists.txt

@@ -653,6 +653,8 @@ set(riscv64_SOURCES
 set(sparc_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
 set(sparcv9_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
 
+set(xtensa_SOURCES ${GENERIC_SOURCES} ${GENERIC_TF_SOURCES})
+
 set(wasm32_SOURCES
   ${GENERIC_TF_SOURCES}
   ${GENERIC_SOURCES}

compiler-rt/lib/crt/crtbegin.c

@@ -69,6 +69,13 @@ __asm__(".pushsection .init,\"ax\",@progbits\n\t"
 __asm__(".pushsection .init,\"ax\",@progbits\n\t"
     "call " __USER_LABEL_PREFIX__ "__do_init\n\t"
     ".popsection");
+#elif defined(__xtensa__)
+__asm__(".pushsection .init.literal,\"ax\",@progbits\n\t"
+    ".popsection\n\t"
+    ".pushsection .init,\"ax\",@progbits\n\t"
+    "movi a8, __do_init\n\t"
+    "callx8 a8\n\t"
+    ".popsection");
 #else
 #error "crtbegin without .init_fini array unimplemented for this architecture"
 #endif // CRT_HAS_INITFINI_ARRAY
@@ -122,6 +129,13 @@ __asm__(".pushsection .fini,\"ax\",@progbits\n\t"
 __asm__(".pushsection .fini,\"ax\",@progbits\n\t"
     "call " __USER_LABEL_PREFIX__ "__do_fini\n\t"
     ".popsection");
+#elif defined(__xtensa__)
+__asm__(".pushsection .fini.literal,\"ax\",@progbits\n\t"
+    ".popsection\n\t"
+    ".pushsection .fini,\"ax\",@progbits\n\t"
+    "movi a8, __do_fini\n\t"
+    "callx8 a8\n\t"
+    ".popsection");
 #else
 #error "crtbegin without .init_fini array unimplemented for this architecture"
 #endif  // CRT_HAS_INIT_FINI_ARRAY