Add x86 SIMD vany_true and x86_ptest

In order to implement SIMD's any_true (https://github.com/WebAssembly/simd/blob/master/proposals/simd/SIMD.md#any-lane-true), we must legalize some instruction (I chose `vany_true`) to a sequence of `PTEST` and `SETNZ`. To emit `PTEST` I added the new CLIF instruction `x86_ptest` and used CLIF's `trueif ne` for `SETNZ`.

cranelift/codegen/meta/src/isa/x86/encodings.rs

@@ -521,6 +521,7 @@ pub(crate) fn define(
     let x86_psll = x86.by_name("x86_psll");
     let x86_psra = x86.by_name("x86_psra");
     let x86_psrl = x86.by_name("x86_psrl");
+    let x86_ptest = x86.by_name("x86_ptest");
     let x86_push = x86.by_name("x86_push");
     let x86_sdivmodx = x86.by_name("x86_sdivmodx");
     let x86_smulx = x86.by_name("x86_smulx");
@@ -1988,6 +1989,10 @@ pub(crate) fn define(
         // xor
         let bxor = bxor.bind(vector(ty, sse_vector_size));
         e.enc_32_64(bxor, rec_fa.opcodes(&PXOR));
+
+        // ptest
+        let x86_ptest = x86_ptest.bind(vector(ty, sse_vector_size));
+        e.enc_32_64_maybe_isap(x86_ptest, rec_fcmp.opcodes(&PTEST), Some(use_sse41_simd));
     }
 
     // SIMD bitcast from I32/I64 to the low bits of a vector (e.g. I64x2); this register movement

cranelift/codegen/meta/src/isa/x86/instructions.rs

@@ -467,5 +467,24 @@ pub(crate) fn define(
         .operands_out(vec![a]),
     );
 
+    let x = &operand("x", TxN);
+    let y = &operand("y", TxN);
+    let f = &operand("f", iflags);
+    ig.push(
+        Inst::new(
+            "x86_ptest",
+            r#"
+        Logical Compare -- PTEST will set the ZF flag if all bits in the result are 0 of the 
+        bitwise AND of the first source operand (first operand) and the second source operand 
+        (second operand). PTEST sets the CF flag if all bits in the result are 0 of the bitwise  
+        AND of the second source operand (second operand) and the logical NOT of the destination
+        operand (first operand).
+        "#,
+            &formats.binary,
+        )
+        .operands_in(vec![x, y])
+        .operands_out(vec![f]),
+    );
+
     ig.build()
 }

cranelift/codegen/meta/src/isa/x86/legalize.rs

@@ -55,12 +55,14 @@ pub(crate) fn define(shared: &mut SharedDefinitions, x86_instructions: &Instruct
     let shuffle = insts.by_name("shuffle");
     let srem = insts.by_name("srem");
     let sshr = insts.by_name("sshr");
+    let trueif = insts.by_name("trueif");
     let udiv = insts.by_name("udiv");
     let umulhi = insts.by_name("umulhi");
     let ushr_imm = insts.by_name("ushr_imm");
     let urem = insts.by_name("urem");
     let ushr = insts.by_name("ushr");
     let vconst = insts.by_name("vconst");
+    let vany_true = insts.by_name("vany_true");
 
     let x86_bsf = x86_instructions.by_name("x86_bsf");
     let x86_bsr = x86_instructions.by_name("x86_bsr");
@@ -69,6 +71,7 @@ pub(crate) fn define(shared: &mut SharedDefinitions, x86_instructions: &Instruct
     let x86_psll = x86_instructions.by_name("x86_psll");
     let x86_psra = x86_instructions.by_name("x86_psra");
     let x86_psrl = x86_instructions.by_name("x86_psrl");
+    let x86_ptest = x86_instructions.by_name("x86_ptest");
     let x86_umulx = x86_instructions.by_name("x86_umulx");
     let x86_smulx = x86_instructions.by_name("x86_smulx");
 
@@ -446,6 +449,16 @@ pub(crate) fn define(shared: &mut SharedDefinitions, x86_instructions: &Instruct
         );
     }
 
+    // SIMD vany_true
+    let ne = Literal::enumerator_for(&imm.intcc, "ne");
+    for ty in ValueType::all_lane_types().filter(allowed_simd_type) {
+        let vany_true = vany_true.bind(vector(ty, sse_vector_size));
+        narrow.legalize(
+            def!(y = vany_true(x)),
+            vec![def!(a = x86_ptest(x, x)), def!(y = trueif(ne, a))],
+        );
+    }
+
     narrow.custom_legalize(shuffle, "convert_shuffle");
     narrow.custom_legalize(extractlane, "convert_extractlane");
     narrow.custom_legalize(insertlane, "convert_insertlane");

cranelift/codegen/meta/src/isa/x86/opcodes.rs

@@ -375,6 +375,10 @@ pub static PSUBUSB: [u8; 3] = [0x66, 0x0f, 0xd8];
 /// and saturate results (SSE2).
 pub static PSUBUSW: [u8; 3] = [0x66, 0x0f, 0xd9];
 
+/// Set ZF if xmm2/m128 AND xmm1 result is all 0s; set CF if xmm2/m128 AND NOT xmm1 result is all
+/// 0s (SSE4.1).
+pub static PTEST: [u8; 4] = [0x66, 0x0f, 0x38, 0x17];
+
 /// Push r{16,32,64}.
 pub static PUSH_REG: [u8; 1] = [0x50];