Make code compatible with LLVM

README.md

@@ -19,6 +19,10 @@ Notes
 
     readelf -l calc.elf
 
+### Build with LLVM
+
+    make AS=clang ASFLAGS="-g -mabi=ilp32e --target=riscv32-unknown-elf -nostdlib -c"
+
 Resources
 ---------
 

debug.s

@@ -57,7 +57,7 @@ regdump_loop:
     lw ra, 0(sp)        # restore contents of ra
     addi sp, sp, 4      # deallocate stack space
     # append ': '
-    li t0, ':
+    li t0, ':'
     sb t0, 0(a0)
     li t0, 0x20
     sb t0, 1(a0)
@@ -73,7 +73,7 @@ regdump_loop:
     lw ra, 0(sp)        # restore contents of ra
     lw a1, 4(sp)        # restore contents of a1 (buffer)
     addi sp, sp, 8      # deallocate stack space
-    li t0, '\n          # append newline
+    li t0, '\n'         # append newline
     sb t0, 8(a1)
 
     # print the register name and value

tests/math_add64.s

@@ -23,8 +23,11 @@ inputs:
     .word 1            # 1
     .word 0x80000000   # 0.5
     .word 2            # 2
-
+inputs_end:
-    .set inputs_end, .-inputs
+  # llvm doesn't like this: error: expected relocatable expression
+  #.set inputs_end, .-inputs
+  # turns out it was right. That was calculating a length, which was
+  # incorrect for how it was used for looping.
 
 .section .bss
 
@@ -33,7 +36,7 @@ buf: .skip 9
 .text
 
 _start:
-    li a0, '\n
+    li a0, '\n'
     la a1, buf
     sb a0, 8(a1)        # append newline to buf
 
@@ -66,7 +69,7 @@ loop:
     li t0, SYSWRITE     # "write" syscall
     li a0, 1            # 1 = standard output (stdout)
     la a1, buf          # load address of output string
-    li a2, '.
+    li a2, '.'
     sb a2, 0(a1)
     li a2, 1            # length of output string
     ecall               # invoke syscall to print the string

tests/tohex.s

@@ -15,7 +15,7 @@ buf: .skip 9
 
 .text
 _start:
-    li a0, '\n
+    li a0, '\n'
     la a1, buf
     sb a0, 8(a1)        # append newline to buf
     li a0, 0xCAFEFEED