ssa: add support for min and max built-in functions

ssa/expr.go

@@ -383,7 +383,7 @@
  token.NEQ - predOpBase: llvm.IntNE,
 }
 
-// EQL NEQ LSS LEQ GTR GEQ == != < <= < >=
+// EQL NEQ LSS LEQ GTR GEQ == != < <= > >=
 func isPredOp(op token.Token) bool {
  return op >= predOpBase && op <= predOpLast
 }
@@ -392,7 +392,7 @@
 // op can be:
 // ADD SUB MUL QUO REM + - * / %
 // AND OR XOR SHL SHR AND_NOT & | ^ << >> &^
-// EQL NEQ LSS LEQ GTR GEQ == != < <= < >=
+// EQL NEQ LSS LEQ GTR GEQ == != < <= > >=
 func (b Builder) BinOp(op token.Token, x, y Expr) Expr {
  if debugInstr {
  log.Printf("BinOp %d, %v, %v\n", op, x.impl, y.impl)
@@ -490,7 +490,7 @@
  llop := logicOpToLLVM[op-logicOpBase]
  return Expr{llvm.CreateBinOp(b.impl, llop, x.impl, y.impl), x.Type}
  }
- case isPredOp(op): // op: == != < <= < >=
+ case isPredOp(op): // op: == != < <= > >=
  prog := b.Prog
  tret := prog.Bool()
  kind := x.kind
@@ -1014,6 +1014,22 @@
  return
 }
 
+// compareSelect performs a series of comparisons and selections based on the
+// given comparison op. It's used to implement operations like min and max.
+//
+// The function iterates through the provided expressions, comparing each with
+// the current result using the specified comparison op. It selects the
+// appropriate value based on the comparison.
+func (b Builder) compareSelect(op token.Token, x Expr, y ...Expr) Expr {
+ ret := x
+ for _, v := range y {
+ cond := b.BinOp(op, ret, v)
+ sel := llvm.CreateSelect(b.impl, cond.impl, ret.impl, v.impl)
+ ret = Expr{sel, ret.Type}
+ }
+ return ret
+}
+
 // A Builtin represents a specific use of a built-in function, e.g. len.
 //
 // Builtins are immutable values. Builtins do not have addresses.
@@ -1124,6 +1140,14 @@
  b.Call(b.Pkg.rtFunc("MapClear"), t, m)
  return
  }
+ case "min":
+ if len(args) > 0 {
+ return b.compareSelect(token.LSS, args[0], args[1:]...)
+ }
+ case "max":
+ if len(args) > 0 {
+ return b.compareSelect(token.GTR, args[0], args[1:]...)
+ }
  }
  panic("todo: " + fn)
 }

ssa/ssa_test.go

@@ -521,3 +521,34 @@ func TestBasicType(t *testing.T) {
  }
  }
 }
+
+func TestCompareSelect(t *testing.T) {
+ prog := NewProgram(nil)
+ pkg := prog.NewPackage("bar", "foo/bar")
+
+ params := types.NewTuple(
+ types.NewVar(0, nil, "a", types.Typ[types.Int]),
+ types.NewVar(0, nil, "b", types.Typ[types.Int]),
+ types.NewVar(0, nil, "c", types.Typ[types.Int]),
+ )
+ rets := types.NewTuple(types.NewVar(0, nil, "", types.Typ[types.Int]))
+ sig := types.NewSignatureType(nil, nil, nil, params, rets, false)
+ fn := pkg.NewFunc("fn", sig, InGo)
+
+ b := fn.MakeBody(1)
+ result := b.compareSelect(token.GTR, fn.Param(0), fn.Param(1), fn.Param(2))
+ b.Return(result)
+
+ assertPkg(t, pkg, `; ModuleID = 'foo/bar'
+source_filename = "foo/bar"
+
+define i64 @fn(i64 %0, i64 %1, i64 %2) {
+_llgo_0:
+ %3 = icmp sgt i64 %0, %1
+ %4 = select i1 %3, i64 %0, i64 %1
+ %5 = icmp sgt i64 %4, %2
+ %6 = select i1 %5, i64 %4, i64 %2
+ ret i64 %6
+}
+`)
+}