Add scalar minmax legalizer

cranelift/codegen/meta/src/shared/legalize.rs

@@ -81,6 +81,8 @@ pub(crate) fn define(insts: &InstructionGroup, imm: &Immediates) -> TransformGro
     let iconst = insts.by_name("iconst");
     let ifcmp = insts.by_name("ifcmp");
     let ifcmp_imm = insts.by_name("ifcmp_imm");
+    let imax = insts.by_name("imax");
+    let imin = insts.by_name("imin");
     let imul = insts.by_name("imul");
     let imul_imm = insts.by_name("imul_imm");
     let ireduce = insts.by_name("ireduce");
@@ -117,6 +119,8 @@ pub(crate) fn define(insts: &InstructionGroup, imm: &Immediates) -> TransformGro
     let uextend = insts.by_name("uextend");
     let uload8 = insts.by_name("uload8");
     let uload16 = insts.by_name("uload16");
+    let umax = insts.by_name("umax");
+    let umin = insts.by_name("umin");
     let umulhi = insts.by_name("umulhi");
     let ushr = insts.by_name("ushr");
     let ushr_imm = insts.by_name("ushr_imm");
@@ -745,6 +749,21 @@ pub(crate) fn define(insts: &InstructionGroup, imm: &Immediates) -> TransformGro
         );
     }
 
+    // Expand scalar [i,u] min/max using icmp and select.
+    for &(inst, cc) in &[(imin, "slt"), (imax, "sgt"), (umin, "ult"), (umax, "ugt")] {
+        let w_cc = Literal::enumerator_for(&imm.intcc, cc);
+        expand.legalize(
+            def!(a = inst(x, y)),
+            vec![def!(c = icmp(w_cc, x, y)), def!(a = select(c, x, y))],
+        );
+        for &int_ty in &[I8, I16] {
+            widen.legalize(
+                def!(a = inst.int_ty(x, y)),
+                vec![def!(c = icmp(w_cc, x, y)), def!(a = select(c, x, y))],
+            )
+        }
+    }
+
     expand.legalize(
         def!(a = icmp_imm(cc, x, y)),
         vec![def!(a1 = iconst(y)), def!(a = icmp(cc, x, a1))],

cranelift/filetests/filetests/isa/x86/scalar-minmax-run.clif

@@ -0,0 +1,68 @@
+test run
+target x86_64
+
+function %imax8(i8, i8) -> i8 {
+block0(v0:i8, v1:i8):
+    v2 = imax v0, v1
+    return v2
+}
+; run: %imax8(1, 10) == 10
+; run: %imax8(-1, 1) == 1
+
+function %imin8(i8, i8) -> i8 {
+block0(v0:i8, v1:i8):
+    v2 = imin v0, v1
+    return v2
+}
+; run: %imin8(1, 10) == 1
+; run: %imin8(-1, 1) == -1
+
+function %umin8(i8, i8) -> i8 {
+block0(v0:i8, v1:i8):
+    v2 = umin v0, v1
+    return v2
+}
+; run: %umin8(1, 10) == 1
+; run: %umin8(-1, 1) == 1
+
+function %umax8(i8, i8) -> i8 {
+block0(v0:i8, v1:i8):
+    v2 = umax v0, v1
+    return v2
+}
+; run: %umax8(1, 10) == 10
+; run: %umax8(-1, 1) == -1
+
+function %imin32(i32, i32) -> i32 {
+block0(v0:i32, v1:i32):
+    v2 = imin v0, v1
+    return v2
+}
+; run: %imin32(1, 10) == 1
+; run: %imin32(-1, 1) == -1
+
+function %imax32(i32, i32) -> i32 {
+block0(v0:i32, v1:i32):
+    v2 = imax v0, v1
+    return v2
+}
+; run: %imin32(1, 10) == 10
+; run: %imin32(-1, 1) == 1
+
+
+function %umin32(i32, i32) -> i32 {
+block0(v0:i32, v1:i32):
+    v2 = umin v0, v1
+    return v2
+}
+; run: %umin32(1, 10) == 1
+; run: %umin32(-1, 1) == 1
+
+
+function %umax32(i32, i32) -> i32 {
+block0(v0:i32, v1:i32):
+    v2 = umax v0, v1
+    return v2
+}
+; run: %umax32(1, 10) == 10
+; run: %umax32(-1, 1) == -1