FFI: Unify stack setup for C calls in interpreter.

9 files changed, 62 insertions, 53 deletions

diff --git a/src/lj_ccall.c b/src/lj_ccall.c
index 04e306eb..9001cb5a 100644
--- a/src/lj_ccall.c
+++ b/src/lj_ccall.c
@@ -20,12 +20,15 @@
 #if LJ_TARGET_X86
 /* -- x86 calling conventions --------------------------------------------- */
 
+#define CCALL_PUSH(arg) \
+  *(GPRArg *)((uint8_t *)cc->stack + nsp) = (GPRArg)(arg), nsp += CTSIZE_PTR
+
 #if LJ_ABI_WIN
 
 #define CCALL_HANDLE_STRUCTRET \
   /* Return structs bigger than 8 by reference (on stack only). */ \
   cc->retref = (sz > 8); \
-  if (cc->retref) cc->stack[nsp++] = (GPRArg)dp;
+  if (cc->retref) CCALL_PUSH(dp);
 
 #define CCALL_HANDLE_COMPLEXRET CCALL_HANDLE_STRUCTRET
 
@@ -40,7 +43,7 @@
     if (ngpr < maxgpr) \
       cc->gpr[ngpr++] = (GPRArg)dp; \
     else \
-      cc->stack[nsp++] = (GPRArg)dp; \
+      CCALL_PUSH(dp); \
   } else {  /* Struct with single FP field ends up in FPR. */ \
     cc->resx87 = ccall_classify_struct(cts, ctr); \
   }
@@ -56,7 +59,7 @@
   if (ngpr < maxgpr) \
     cc->gpr[ngpr++] = (GPRArg)dp; \
   else \
-    cc->stack[nsp++] = (GPRArg)dp;
+    CCALL_PUSH(dp);
 
 #endif
 
@@ -67,7 +70,7 @@
     if (ngpr < maxgpr) \
       cc->gpr[ngpr++] = (GPRArg)dp; \
     else \
-      cc->stack[nsp++] = (GPRArg)dp; \
+      CCALL_PUSH(dp); \
   }
 
 #endif
@@ -278,8 +281,8 @@
   if (ngpr < maxgpr) { \
     dp = &cc->gpr[ngpr]; \
     if (ngpr + n > maxgpr) { \
-      nsp += ngpr + n - maxgpr;  /* Assumes contiguous gpr/stack fields. */ \
-      if (nsp > CCALL_MAXSTACK) goto err_nyi;  /* Too many arguments. */ \
+      nsp += (ngpr + n - maxgpr) * CTSIZE_PTR;  /* Assumes contiguous gpr/stack fields. */ \
+      if (nsp > CCALL_SIZE_STACK) goto err_nyi;  /* Too many arguments. */ \
       ngpr = maxgpr; \
     } else { \
       ngpr += n; \
@@ -471,8 +474,8 @@
   if (ngpr < maxgpr) { \
     dp = &cc->gpr[ngpr]; \
     if (ngpr + n > maxgpr) { \
-     nsp += ngpr + n - maxgpr;  /* Assumes contiguous gpr/stack fields. */ \
-     if (nsp > CCALL_MAXSTACK) goto err_nyi;  /* Too many arguments. */ \
+     nsp += (ngpr + n - maxgpr) * CTSIZE_PTR;  /* Assumes contiguous gpr/stack fields. */ \
+     if (nsp > CCALL_SIZE_STACK) goto err_nyi;  /* Too many arguments. */ \
      ngpr = maxgpr; \
     } else { \
      ngpr += n; \
@@ -565,8 +568,8 @@
   if (ngpr < maxgpr) { \
     dp = &cc->gpr[ngpr]; \
     if (ngpr + n > maxgpr) { \
-      nsp += ngpr + n - maxgpr;  /* Assumes contiguous gpr/stack fields. */ \
-      if (nsp > CCALL_MAXSTACK) goto err_nyi;  /* Too many arguments. */ \
+      nsp += (ngpr + n - maxgpr) * CTSIZE_PTR;  /* Assumes contiguous gpr/stack fields. */ \
+      if (nsp > CCALL_SIZE_STACK) goto err_nyi;  /* Too many arguments. */ \
       ngpr = maxgpr; \
     } else { \
       ngpr += n; \
@@ -698,10 +701,11 @@ static int ccall_struct_arg(CCallState *cc, CTState *cts, CType *d, int *rcl,
   lj_cconv_ct_tv(cts, d, (uint8_t *)dp, o, CCF_ARG(narg));
   if (ccall_struct_reg(cc, cts, dp, rcl)) {
     /* Register overflow? Pass on stack. */
-    MSize nsp = cc->nsp, n = rcl[1] ? 2 : 1;
-    if (nsp + n > CCALL_MAXSTACK) return 1;  /* Too many arguments. */
-    cc->nsp = nsp + n;
-    memcpy(&cc->stack[nsp], dp, n*CTSIZE_PTR);
+    MSize nsp = cc->nsp, sz = rcl[1] ? 2*CTSIZE_PTR : CTSIZE_PTR;
+    if (nsp + sz > CCALL_SIZE_STACK)
+      return 1;  /* Too many arguments. */
+    cc->nsp = nsp + sz;
+    memcpy((uint8_t *)cc->stack + nsp, dp, sz);
   }
   return 0;  /* Ok. */
 }
@@ -1022,22 +1026,23 @@ static int ccall_set_args(lua_State *L, CTState *cts, CType *ct,
     } else {
       sz = CTSIZE_PTR;
     }
-    sz = (sz + CTSIZE_PTR-1) & ~(CTSIZE_PTR-1);
-    n = sz / CTSIZE_PTR;  /* Number of GPRs or stack slots needed. */
+    n = (sz + CTSIZE_PTR-1) / CTSIZE_PTR;  /* Number of GPRs or stack slots needed. */
 
     CCALL_HANDLE_REGARG  /* Handle register arguments. */
 
     /* Otherwise pass argument on stack. */
-    if (CCALL_ALIGN_STACKARG && !rp && (d->info & CTF_ALIGN) > CTALIGN_PTR) {
-      MSize align = (1u << ctype_align(d->info-CTALIGN_PTR)) -1;
-      nsp = (nsp + align) & ~align;  /* Align argument on stack. */
+    if (CCALL_ALIGN_STACKARG) {  /* Align argument on stack. */
+      MSize align = (1u << ctype_align(d->info)) - 1;
+      if (rp)
+        align = CTSIZE_PTR-1;
+      nsp = (nsp + align) & ~align;
     }
-    if (nsp + n > CCALL_MAXSTACK) {  /* Too many arguments. */
+    dp = ((uint8_t *)cc->stack) + nsp;
+    nsp += n * CTSIZE_PTR;
+    if (nsp > CCALL_SIZE_STACK) {  /* Too many arguments. */
     err_nyi:
       lj_err_caller(L, LJ_ERR_FFI_NYICALL);
     }
-    dp = &cc->stack[nsp];
-    nsp += n;
     isva = 0;
 
   done:
@@ -1099,10 +1104,10 @@ static int ccall_set_args(lua_State *L, CTState *cts, CType *ct,
 #if LJ_TARGET_X64 || (LJ_TARGET_PPC && !LJ_ABI_SOFTFP)
   cc->nfpr = nfpr;  /* Required for vararg functions. */
 #endif
-  cc->nsp = nsp;
-  cc->spadj = (CCALL_SPS_FREE + CCALL_SPS_EXTRA)*CTSIZE_PTR;
-  if (nsp > CCALL_SPS_FREE)
-    cc->spadj += (((nsp-CCALL_SPS_FREE)*CTSIZE_PTR + 15u) & ~15u);
+  cc->nsp = (nsp + CTSIZE_PTR-1) & ~(CTSIZE_PTR-1);
+  cc->spadj = (CCALL_SPS_FREE + CCALL_SPS_EXTRA) * CTSIZE_PTR;
+  if (cc->nsp > CCALL_SPS_FREE * CTSIZE_PTR)
+    cc->spadj += (((cc->nsp - CCALL_SPS_FREE * CTSIZE_PTR) + 15u) & ~15u);
   return gcsteps;
 }
 
diff --git a/src/lj_ccall.h b/src/lj_ccall.h
index 547415f7..57300817 100644
--- a/src/lj_ccall.h
+++ b/src/lj_ccall.h
@@ -152,14 +152,15 @@ typedef union FPRArg {
 LJ_STATIC_ASSERT(CCALL_NUM_GPR <= CCALL_MAX_GPR);
 LJ_STATIC_ASSERT(CCALL_NUM_FPR <= CCALL_MAX_FPR);
 
-#define CCALL_MAXSTACK          32
+#define CCALL_NUM_STACK         31
+#define CCALL_SIZE_STACK        (CCALL_NUM_STACK * CTSIZE_PTR)
 
 /* -- C call state -------------------------------------------------------- */
 
 typedef LJ_ALIGN(CCALL_ALIGN_CALLSTATE) struct CCallState {
   void (*func)(void);           /* Pointer to called function. */
   uint32_t spadj;               /* Stack pointer adjustment. */
-  uint8_t nsp;                  /* Number of stack slots. */
+  uint8_t nsp;                  /* Number of bytes on stack. */
   uint8_t retref;               /* Return value by reference. */
 #if LJ_TARGET_X64
   uint8_t ngpr;                 /* Number of arguments in GPRs. */
@@ -178,7 +179,7 @@ typedef LJ_ALIGN(CCALL_ALIGN_CALLSTATE) struct CCallState {
   FPRArg fpr[CCALL_NUM_FPR];    /* Arguments/results in FPRs. */
 #endif
   GPRArg gpr[CCALL_NUM_GPR];    /* Arguments/results in GPRs. */
-  GPRArg stack[CCALL_MAXSTACK]; /* Stack slots. */
+  GPRArg stack[CCALL_NUM_STACK];        /* Stack slots. */
 } CCallState;
 
 /* -- C call handling ----------------------------------------------------- */
diff --git a/src/vm_arm.dasc b/src/vm_arm.dasc
index 4f0798e0..0d1ea95f 100644
--- a/src/vm_arm.dasc
+++ b/src/vm_arm.dasc
@@ -2571,16 +2571,16 @@ static void build_subroutines(BuildCtx *ctx)
   |.endif
   |  mov r11, sp
   |  sub sp, sp, CARG1                  // Readjust stack.
-  |   subs CARG2, CARG2, #1
+  |   subs CARG2, CARG2, #4
   |.if HFABI
   |  vldm RB, {d0-d7}
   |.endif
   |    ldr RB, CCSTATE->func
   |   bmi >2
   |1:  // Copy stack slots.
-  |  ldr CARG4, [CARG3, CARG2, lsl #2]
-  |  str CARG4, [sp, CARG2, lsl #2]
-  |  subs CARG2, CARG2, #1
+  |  ldr CARG4, [CARG3, CARG2]
+  |  str CARG4, [sp, CARG2]
+  |  subs CARG2, CARG2, #4
   |  bpl <1
   |2:
   |  ldrd CARG12, CCSTATE->gpr[0]
diff --git a/src/vm_arm64.dasc b/src/vm_arm64.dasc
index a7a9392c..698b4210 100644
--- a/src/vm_arm64.dasc
+++ b/src/vm_arm64.dasc
@@ -2222,14 +2222,14 @@ static void build_subroutines(BuildCtx *ctx)
   |  ldr TMP0w, CCSTATE:x0->spadj
   |   ldrb TMP1w, CCSTATE->nsp
   |    add TMP2, CCSTATE, #offsetof(CCallState, stack)
-  |   subs TMP1, TMP1, #1
+  |   subs TMP1, TMP1, #8
   |    ldr TMP3, CCSTATE->func
   |  sub sp, sp, TMP0
   |   bmi >2
   |1:  // Copy stack slots
-  |  ldr TMP0, [TMP2, TMP1, lsl #3]
-  |  str TMP0, [sp, TMP1, lsl #3]
-  |  subs TMP1, TMP1, #1
+  |  ldr TMP0, [TMP2, TMP1]
+  |  str TMP0, [sp, TMP1]
+  |  subs TMP1, TMP1, #8
   |  bpl <1
   |2:
   |  ldp x0, x1, CCSTATE->gpr[0]
diff --git a/src/vm_mips.dasc b/src/vm_mips.dasc
index 94a878b9..f276745c 100644
--- a/src/vm_mips.dasc
+++ b/src/vm_mips.dasc
@@ -2951,7 +2951,6 @@ static void build_subroutines(BuildCtx *ctx)
   |  move TMP2, sp
   |  subu sp, sp, TMP1
   |  sw ra, -4(TMP2)
-  |   sll CARG2, CARG2, 2
   |  sw r16, -8(TMP2)
   |  sw CCSTATE, -12(TMP2)
   |  move r16, TMP2
diff --git a/src/vm_mips64.dasc b/src/vm_mips64.dasc
index f8e181ee..6c215f2b 100644
--- a/src/vm_mips64.dasc
+++ b/src/vm_mips64.dasc
@@ -3065,7 +3065,6 @@ static void build_subroutines(BuildCtx *ctx)
   |  move TMP2, sp
   |  dsubu sp, sp, TMP1
   |  sd ra, -8(TMP2)
-  |   sll CARG2, CARG2, 3
   |  sd r16, -16(TMP2)
   |  sd CCSTATE, -24(TMP2)
   |  move r16, TMP2
diff --git a/src/vm_ppc.dasc b/src/vm_ppc.dasc
index 73a70a00..f2e5a08f 100644
--- a/src/vm_ppc.dasc
+++ b/src/vm_ppc.dasc
@@ -3269,14 +3269,13 @@ static void build_subroutines(BuildCtx *ctx)
   |    stw TMP0, 4(sp)
   |   cmpwi cr1, CARG3, 0
   |  mr TMP2, sp
-  |   addic. CARG2, CARG2, -1
+  |   addic. CARG2, CARG2, -4
   |  stwux sp, sp, TMP1
   |   crnot 4*cr1+eq, 4*cr1+eq          // For vararg calls.
   |  stw r14, -4(TMP2)
   |  stw CCSTATE, -8(TMP2)
   |  mr r14, TMP2
   |  la TMP1, CCSTATE->stack
-  |   slwi CARG2, CARG2, 2
   |   blty >2
   |  la TMP2, 8(sp)
   |1:
diff --git a/src/vm_x64.dasc b/src/vm_x64.dasc
index a8649b4e..3635ba28 100644
--- a/src/vm_x64.dasc
+++ b/src/vm_x64.dasc
@@ -2755,12 +2755,12 @@ static void build_subroutines(BuildCtx *ctx)
   |
   |  // Copy stack slots.
   |  movzx ecx, byte CCSTATE->nsp
-  |  sub ecx, 1
+  |  sub ecx, 8
   |  js >2
   |1:
-  |  mov rax, [CCSTATE+rcx*8+offsetof(CCallState, stack)]
-  |  mov [rsp+rcx*8+CCALL_SPS_EXTRA*8], rax
-  |  sub ecx, 1
+  |  mov rax, [CCSTATE+rcx+offsetof(CCallState, stack)]
+  |  mov [rsp+rcx+CCALL_SPS_EXTRA*8], rax
+  |  sub ecx, 8
   |  jns <1
   |2:
   |
diff --git a/src/vm_x86.dasc b/src/vm_x86.dasc
index bda9d7d7..c44a24ff 100644
--- a/src/vm_x86.dasc
+++ b/src/vm_x86.dasc
@@ -3314,19 +3314,25 @@ static void build_subroutines(BuildCtx *ctx)
   |
   |  // Copy stack slots.
   |  movzx ecx, byte CCSTATE->nsp
-  |  sub ecx, 1
+  |.if X64
+  |  sub ecx, 8
   |  js >2
   |1:
-  |.if X64
-  |  mov rax, [CCSTATE+rcx*8+offsetof(CCallState, stack)]
-  |  mov [rsp+rcx*8+CCALL_SPS_EXTRA*8], rax
+  |  mov rax, [CCSTATE+rcx+offsetof(CCallState, stack)]
+  |  mov [rsp+rcx+CCALL_SPS_EXTRA*8], rax
+  |  sub ecx, 8
+  |  jns <1
+  |2:
   |.else
-  |  mov eax, [CCSTATE+ecx*4+offsetof(CCallState, stack)]
-  |  mov [esp+ecx*4], eax
-  |.endif
-  |  sub ecx, 1
+  |  sub ecx, 4
+  |  js >2
+  |1:
+  |  mov eax, [CCSTATE+ecx+offsetof(CCallState, stack)]
+  |  mov [esp+ecx], eax
+  |  sub ecx, 4
   |  jns <1
   |2:
+  |.endif
   |
   |.if X64
   |  movzx eax, byte CCSTATE->nfpr