Revert "YJIT: implement `expandarray_rhs_too_small` case (#8153)"

This reverts commit 3b88a0bee8.

  This commit break aarch64 platform and Apple Silicon

yjit/src/backend/x86_64/mod.rs

@@ -428,31 +428,11 @@ impl Assembler
             }
         }
 
-        fn emit_csel(
-            cb: &mut CodeBlock,
-            truthy: Opnd,
-            falsy: Opnd,
-            out: Opnd,
-            cmov_fn: fn(&mut CodeBlock, X86Opnd, X86Opnd),
-            cmov_neg: fn(&mut CodeBlock, X86Opnd, X86Opnd)){
-
-            // Assert that output is a register
-            out.unwrap_reg();
-
-            // If the truthy value is a memory operand
-            if let Opnd::Mem(_) = truthy {
-                if out != falsy {
-                    mov(cb, out.into(), falsy.into());
-                }
-
-                cmov_fn(cb, out.into(), truthy.into());
-            } else {
-                if out != truthy {
-                    mov(cb, out.into(), truthy.into());
-                }
-
-                cmov_neg(cb, out.into(), falsy.into());
+        fn emit_csel(cb: &mut CodeBlock, truthy: Opnd, falsy: Opnd, out: Opnd, cmov_fn: fn(&mut CodeBlock, X86Opnd, X86Opnd)) {
+            if out != truthy {
+                mov(cb, out.into(), truthy.into());
             }
+            cmov_fn(cb, out.into(), falsy.into());
         }
 
         //dbg!(&self.insns);
@@ -744,28 +724,28 @@ impl Assembler
                 Insn::Breakpoint => int3(cb),
 
                 Insn::CSelZ { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovz, cmovnz);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovnz);
                 },
                 Insn::CSelNZ { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovnz, cmovz);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovz);
                 },
                 Insn::CSelE { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmove, cmovne);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovne);
                 },
                 Insn::CSelNE { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovne, cmove);
+                    emit_csel(cb, *truthy, *falsy, *out, cmove);
                 },
                 Insn::CSelL { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovl, cmovge);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovge);
                 },
                 Insn::CSelLE { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovle, cmovg);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovg);
                 },
                 Insn::CSelG { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovg, cmovle);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovle);
                 },
                 Insn::CSelGE { truthy, falsy, out } => {
-                    emit_csel(cb, *truthy, *falsy, *out, cmovge, cmovl);
+                    emit_csel(cb, *truthy, *falsy, *out, cmovl);
                 }
                 Insn::LiveReg { .. } => (), // just a reg alloc signal, no code
                 Insn::PadInvalPatch => {
@@ -1197,26 +1177,4 @@ mod tests {
             0x23: call rax
         "});
     }
-
-    #[test]
-    fn test_cmov_mem() {
-        let (mut asm, mut cb) = setup_asm();
-
-        let top = Opnd::mem(64, SP, 0);
-        let ary_opnd = SP;
-        let array_len_opnd = Opnd::mem(64, SP, 16);
-
-        asm.cmp(array_len_opnd, 1.into());
-        let elem_opnd = asm.csel_g(Opnd::mem(64, ary_opnd, 0), Qnil.into());
-        asm.mov(top, elem_opnd);
-
-        asm.compile_with_num_regs(&mut cb, 1);
-
-        assert_disasm!(cb, "48837b1001b804000000480f4f03488903", {"
-            0x0: cmp qword ptr [rbx + 0x10], 1
-            0x5: mov eax, 4
-            0xa: cmovg rax, qword ptr [rbx]
-            0xe: mov qword ptr [rbx], rax
-        "});
-    }
 }

yjit/src/codegen.rs

@@ -1517,6 +1517,11 @@ fn gen_expandarray(
     let array_reg = asm.load(array_opnd);
     let array_len_opnd = get_array_len(asm, array_reg);
 
+    // Only handle the case where the number of values in the array is greater
+    // than or equal to the number of values requested.
+    asm.cmp(array_len_opnd, num.into());
+    asm.jl(Target::side_exit(Counter::expandarray_rhs_too_small));
+
     // Load the address of the embedded array into REG1.
     // (struct RArray *)(obj)->as.ary
     let array_reg = asm.load(array_opnd);
@@ -1537,11 +1542,7 @@ fn gen_expandarray(
     for i in (0..num).rev() {
         let top = asm.stack_push(Type::Unknown);
         let offset = i32::try_from(i * SIZEOF_VALUE).unwrap();
-
-        // If the element index is less than the length of the array, load it
-        asm.cmp(array_len_opnd, i.into());
-        let elem_opnd = asm.csel_g(Opnd::mem(64, ary_opnd, offset), Qnil.into());
-        asm.mov(top, elem_opnd);
+        asm.mov(top, Opnd::mem(64, ary_opnd, offset));
     }
 
     Some(KeepCompiling)