Add conditional branch encodings for RISC-V.

Not all br_icmp opcodes are present in the ISA. The missing ones can be
reached by commuting operands.

Don't attempt to encode EBB offsets yet. For now just emit an EBB
relocation for the branch instruction.

cranelift/filetests/isa/riscv/binary32.cton

@@ -75,5 +75,21 @@ ebb0:
     [-,%x7]     v140 = iconst.i32 0x12345000            ; bin: 123453b7
     [-,%x16]    v141 = iconst.i32 0xffffffff_fedcb000   ; bin: fedcb837
 
+
+    ; Control Transfer Instructions
+
+    ; beq
+    br_icmp eq, v1, v2, ebb0            ; bin: Branch(ebb0) 01550063
+    ; bne
+    br_icmp ne, v1, v2, ebb0            ; bin: Branch(ebb0) 01551063
+    ; blt
+    br_icmp slt, v1, v2, ebb0           ; bin: Branch(ebb0) 01554063
+    ; bge
+    br_icmp sge, v1, v2, ebb0           ; bin: Branch(ebb0) 01555063
+    ; bltu
+    br_icmp ult, v1, v2, ebb0           ; bin: Branch(ebb0) 01556063
+    ; bgeu
+    br_icmp uge, v1, v2, ebb0           ; bin: Branch(ebb0) 01557063
+
     return
 }

cranelift/src/filetest/binemit.rs

@@ -25,6 +25,7 @@ pub fn subtest(parsed: &TestCommand) -> Result<Box<SubTest>> {
 
 // Code sink that generates text.
 struct TextSink {
+    rnames: &'static [&'static str],
     text: String,
 }
 
@@ -45,12 +46,16 @@ impl binemit::CodeSink for TextSink {
         write!(self.text, "{:016x} ", x).unwrap();
     }
 
-    fn reloc_func(&mut self, _: binemit::Reloc, _: ir::FuncRef) {
-        unimplemented!()
+    fn reloc_ebb(&mut self, reloc: binemit::Reloc, ebb: ir::Ebb) {
+        write!(self.text, "{}({}) ", self.rnames[reloc.0 as usize], ebb).unwrap();
     }
 
-    fn reloc_jt(&mut self, _: binemit::Reloc, _: ir::JumpTable) {
-        unimplemented!()
+    fn reloc_func(&mut self, reloc: binemit::Reloc, fref: ir::FuncRef) {
+        write!(self.text, "{}({}) ", self.rnames[reloc.0 as usize], fref).unwrap();
+    }
+
+    fn reloc_jt(&mut self, reloc: binemit::Reloc, jt: ir::JumpTable) {
+        write!(self.text, "{}({}) ", self.rnames[reloc.0 as usize], jt).unwrap();
     }
 }
 
@@ -73,7 +78,10 @@ impl SubTest for TestBinEmit {
         // value locations. The current error reporting is just crashing...
         let mut func = func.into_owned();
 
-        let mut sink = TextSink { text: String::new() };
+        let mut sink = TextSink {
+            rnames: isa.reloc_names(),
+            text: String::new(),
+        };
 
         for comment in &context.details.comments {
             if let Some(want) = match_directive(comment.text, "bin:") {

cranelift/test-all.sh

@@ -56,7 +56,7 @@ fi
 if [ -n "$needcheck" ]; then
     banner $(python --version 2>&1)
     $topdir/lib/cretonne/meta/check.sh
-    touch $tsfile
+    touch $tsfile || echo no target directory
 fi
 
 PKGS="cretonne cretonne-reader cretonne-tools filecheck"