The Tor Browser: xpcom/reflect/xptcall/src/md/unix/xptcinvoke_x86_64

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-

     2  *

     3  * This Source Code Form is subject to the terms of the Mozilla Public

     4  * License, v. 2.0. If a copy of the MPL was not distributed with this

     5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     7 // Platform specific code to invoke XPCOM methods on native objects

     9 #include "xptcprivate.h"

    10 #include "alloca.h"

    12 // 6 integral parameters are passed in registers

    13 const uint32_t GPR_COUNT = 6;

    15 // 8 floating point parameters are passed in SSE registers

    16 const uint32_t FPR_COUNT = 8;

    18 // Remember that these 'words' are 64-bit long

    19 static inline void

    20 invoke_count_words(uint32_t paramCount, nsXPTCVariant * s,

    21                    uint32_t & nr_gpr, uint32_t & nr_fpr, uint32_t & nr_stack)

    22 {

    23     nr_gpr = 1; // skip one GP register for 'that'

    24     nr_fpr = 0;

    25     nr_stack = 0;

    27     /* Compute number of eightbytes of class MEMORY.  */

    28     for (uint32_t i = 0; i < paramCount; i++, s++) {

    29         if (!s->IsPtrData()

    30             && (s->type == nsXPTType::T_FLOAT || s->type == nsXPTType::T_DOUBLE)) {

    31             if (nr_fpr < FPR_COUNT)

    32                 nr_fpr++;

    33             else

    34                 nr_stack++;

    35         }

    36         else {

    37             if (nr_gpr < GPR_COUNT)

    38                 nr_gpr++;

    39             else

    40                 nr_stack++;

    41         }

    42     }

    43 }

    45 static void

    46 invoke_copy_to_stack(uint64_t * d, uint32_t paramCount, nsXPTCVariant * s,

    47                      uint64_t * gpregs, double * fpregs)

    48 {

    49     uint32_t nr_gpr = 1; // skip one GP register for 'that'

    50     uint32_t nr_fpr = 0;

    51     uint64_t value;

    53     for (uint32_t i = 0; i < paramCount; i++, s++) {

    54         if (s->IsPtrData())

    55             value = (uint64_t) s->ptr;

    56         else {

    57             switch (s->type) {

    58             case nsXPTType::T_FLOAT:                                break;

    59             case nsXPTType::T_DOUBLE:                               break;

    60             case nsXPTType::T_I8:     value = s->val.i8;            break;

    61             case nsXPTType::T_I16:    value = s->val.i16;           break;

    62             case nsXPTType::T_I32:    value = s->val.i32;           break;

    63             case nsXPTType::T_I64:    value = s->val.i64;           break;

    64             case nsXPTType::T_U8:     value = s->val.u8;            break;

    65             case nsXPTType::T_U16:    value = s->val.u16;           break;

    66             case nsXPTType::T_U32:    value = s->val.u32;           break;

    67             case nsXPTType::T_U64:    value = s->val.u64;           break;

    68             case nsXPTType::T_BOOL:   value = s->val.b;             break;

    69             case nsXPTType::T_CHAR:   value = s->val.c;             break;

    70             case nsXPTType::T_WCHAR:  value = s->val.wc;            break;

    71             default:                  value = (uint64_t) s->val.p;  break;

    72             }

    73         }

    75         if (!s->IsPtrData() && s->type == nsXPTType::T_DOUBLE) {

    76             if (nr_fpr < FPR_COUNT)

    77                 fpregs[nr_fpr++] = s->val.d;

    78             else {

    79                 *((double *)d) = s->val.d;

    80                 d++;

    81             }

    82         }

    83         else if (!s->IsPtrData() && s->type == nsXPTType::T_FLOAT) {

    84             if (nr_fpr < FPR_COUNT)

    85                 // The value in %xmm register is already prepared to

    86                 // be retrieved as a float. Therefore, we pass the

    87                 // value verbatim, as a double without conversion.

    88                 fpregs[nr_fpr++] = s->val.d;

    89             else {

    90                 *((float *)d) = s->val.f;

    91                 d++;

    92             }

    93         }

    94         else {

    95             if (nr_gpr < GPR_COUNT)

    96                 gpregs[nr_gpr++] = value;

    97             else

    98                 *d++ = value;

    99         }

   100     }

   101 }

   103 EXPORT_XPCOM_API(nsresult)

   104 NS_InvokeByIndex(nsISupports * that, uint32_t methodIndex,

   105                  uint32_t paramCount, nsXPTCVariant * params)

   106 {

   107     uint32_t nr_gpr, nr_fpr, nr_stack;

   108     invoke_count_words(paramCount, params, nr_gpr, nr_fpr, nr_stack);

   110     // Stack, if used, must be 16-bytes aligned

   111     if (nr_stack)

   112         nr_stack = (nr_stack + 1) & ~1;

   114     // Load parameters to stack, if necessary

   115     uint64_t *stack = (uint64_t *) __builtin_alloca(nr_stack * 8);

   116     uint64_t gpregs[GPR_COUNT];

   117     double fpregs[FPR_COUNT];

   118     invoke_copy_to_stack(stack, paramCount, params, gpregs, fpregs);

   120     switch (nr_fpr) {

   121       case 8: asm("movupd %0, %xmm7" : : "xmm7" (fpregs[7]));

   122       case 7: asm("movupd %0, %xmm6" : : "xmm6" (fpregs[6]));

   123       case 6: asm("movupd %0, %xmm5" : : "xmm5" (fpregs[5]));

   124       case 5: asm("movupd %0, %xmm4" : : "xmm4" (fpregs[4]));

   125       case 4: asm("movupd %0, %xmm3" : : "xmm3" (fpregs[3]));

   126       case 3: asm("movupd %0, %xmm2" : : "xmm2" (fpregs[2]));

   127       case 2: asm("movupd %0, %xmm1" : : "xmm1" (fpregs[1]));

   128       case 1: asm("movupd %0, %xmm0" : : "xmm0" (fpregs[0]));

   129       case 0:;

   130     }

   132     // Ensure that assignments to SSE registers won't be optimized away

   133     asm("" ::: "xmm0", "xmm1", "xmm2", "xmm3", "xmm4", "xmm5", "xmm6", "xmm7");

   135     // Get pointer to method

   136     uint64_t methodAddress = *((uint64_t *)that);

   137     methodAddress += 16 + 8 * methodIndex;

   138     methodAddress = *((uint64_t *)methodAddress);

   140     typedef uint32_t (*Method)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t, uint64_t);

   141     uint32_t result = ((Method)methodAddress)((uint64_t)that, gpregs[1], gpregs[2], gpregs[3], gpregs[4], gpregs[5]);

   142     return result;

   143 }

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