[jit] Use xmm5 as an fp scratch register on winx64.

mono/mini/mini-amd64.c

@@ -4442,8 +4442,8 @@ mono_arch_output_basic_block (MonoCompile *cfg, MonoBasicBlock *bb)
 			break;
 		case OP_STORER4_MEMBASE_REG:
 			/* This requires a double->single conversion */
-			amd64_sse_cvtsd2ss_reg_reg (code, AMD64_XMM15, ins->sreg1);
-			amd64_sse_movss_membase_reg (code, ins->inst_destbasereg, ins->inst_offset, AMD64_XMM15);
+			amd64_sse_cvtsd2ss_reg_reg (code, MONO_ARCH_FP_SCRATCH_REG, ins->sreg1);
+			amd64_sse_movss_membase_reg (code, ins->inst_destbasereg, ins->inst_offset, MONO_ARCH_FP_SCRATCH_REG);
 			break;
 		case OP_LOADR4_MEMBASE:
 			amd64_sse_movss_reg_membase (code, ins->dreg, ins->inst_basereg, ins->inst_offset);
@@ -5346,8 +5346,8 @@ mono_arch_output_basic_block (MonoCompile *cfg, MonoBasicBlock *bb)
 			break;
 		case OP_EXTRACT_I8:
 			if (ins->inst_c0) {
-				amd64_movhlps_reg_reg (code, AMD64_XMM15, ins->sreg1);
-				amd64_movd_reg_xreg_size (code, ins->dreg, AMD64_XMM15, 8);
+				amd64_movhlps_reg_reg (code, MONO_ARCH_FP_SCRATCH_REG, ins->sreg1);
+				amd64_movd_reg_xreg_size (code, ins->dreg, MONO_ARCH_FP_SCRATCH_REG, 8);
 			} else {
 				amd64_movd_reg_xreg_size (code, ins->dreg, ins->sreg1, 8);
 			}
@@ -5399,11 +5399,11 @@ mono_arch_output_basic_block (MonoCompile *cfg, MonoBasicBlock *bb)
 			amd64_sse_pinsrw_reg_reg_imm (code, ins->dreg, ins->sreg2, ins->inst_c0 * 2 + 1);
 			break;
 		case OP_INSERTX_I8_SLOW:
-			amd64_movd_xreg_reg_size(code, AMD64_XMM15, ins->sreg2, 8);
+			amd64_movd_xreg_reg_size(code, MONO_ARCH_FP_SCRATCH_REG, ins->sreg2, 8);
 			if (ins->inst_c0)
-				amd64_movlhps_reg_reg (code, ins->dreg, AMD64_XMM15);
+				amd64_movlhps_reg_reg (code, ins->dreg, MONO_ARCH_FP_SCRATCH_REG);
 			else
-				amd64_sse_movsd_reg_reg (code, ins->dreg, AMD64_XMM15);
+				amd64_sse_movsd_reg_reg (code, ins->dreg, MONO_ARCH_FP_SCRATCH_REG);
 			break;
 
 		case OP_INSERTX_R4_SLOW:

mono/mini/mini-amd64.h

@@ -102,14 +102,17 @@ struct sigcontext {
 
 #define MONO_ARCH_FP_RETURN_REG AMD64_XMM0
 
-/* xmm15 is reserved for use by some opcodes */
 #ifdef TARGET_WIN32
-#define MONO_ARCH_CALLEE_FREGS 0x3f
+/* xmm5 is used as a scratch register */
+#define MONO_ARCH_CALLEE_FREGS 0x1f
 /* xmm6:xmm15 */
-#define MONO_ARCH_CALLEE_SAVED_FREGS (0x7fff - 0x3f)
+#define MONO_ARCH_CALLEE_SAVED_FREGS (0xffff - 0x3f)
+#define MONO_ARCH_FP_SCRATCH_REG AMD64_XMM5
 #else
+/* xmm15 is used as a scratch register */
 #define MONO_ARCH_CALLEE_FREGS 0x7fff
 #define MONO_ARCH_CALLEE_SAVED_FREGS 0
+#define MONO_ARCH_FP_SCRATCH_REG AMD64_XMM15
 #endif
 
 #define MONO_MAX_XREGS MONO_MAX_FREGS