Review fixes

test/first_party/CMakeLists.txt

@@ -43,15 +43,26 @@ if (CLANG_BIN)
     else()
         message(WARNING "Your Clang compiler does not support RISC-V (see '${CLANG_BIN} -print-targets'). Please download one from https://github.com/llvm/llvm-project/releases")
     endif()
-elseif (GCC_BIN_RV64)
-    set(CROSS_COMPILER_COMMAND_RV64 ${GCC_BIN_RV64})
-    if (GCC_BIN_RV32)
+endif()
+
+# Prefer riscv32-unknown-elf-gcc to riscv64-unknown-elf-gcc for RV32.
+if (GCC_BIN_RV32)
+    if (NOT CROSS_COMPILER_COMMAND_RV32)
         set(CROSS_COMPILER_COMMAND_RV32 ${GCC_BIN_RV32})
-    else()
-        # Hope it has multilib support. I'm not sure how to test that.
+    endif()
+endif()
+
+if (GCC_BIN_RV64)
+    if (NOT CROSS_COMPILER_COMMAND_RV32)
+        # It might support multilib.
         set(CROSS_COMPILER_COMMAND_RV32 ${GCC_BIN_RV64})
     endif()
-else()
+    if (NOT CROSS_COMPILER_COMMAND_RV64)
+        set(CROSS_COMPILER_COMMAND_RV64 ${GCC_BIN_RV64})
+    endif()
+endif()
+
+if (NOT CROSS_COMPILER_COMMAND_RV32 OR NOT CROSS_COMPILER_COMMAND_RV64)
     message(FATAL_ERROR "No suitable cross-compiler found. We recommend downloading Clang from https://github.com/llvm/llvm-project/releases")
 endif()
 
@@ -94,7 +105,7 @@ foreach (xlen IN ITEMS 32 64)
                 # Indicate we are building in a standalone environment. Implies -fno-builtin
                 # so the compiler won't assume that memcpy etc. are available.
                 -ffreestanding
-                # Don't try to link with libc or libc.
+                # Don't try to link with libc or libm.
                 -nostdlib
                 # Generate a statically linked binary.
                 -static