From 65ace14e184807df026e985e073b3b5c5aaf576c Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Thu, 1 Jun 2023 23:16:48 +0200
Subject: basic ABI lowering of aggregates

---
 amd64/all.h  |  15 ---------
 amd64/sysv.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+), 15 deletions(-)

(limited to 'amd64')

diff --git a/amd64/all.h b/amd64/all.h
index fdd759a..915d93a 100644
--- a/amd64/all.h
+++ b/amd64/all.h
@@ -1,6 +1,5 @@
 #include "../ir.h"
 
-
 #define LIST_REGS(_)                                               \
    _(RAX) _(RCX) _(RDX) _(RBX) _(RSP) _(RBP) _(RSI) _(RDI)         \
    _(R8) _(R9) _(R10) _(R11) _(R12) _(R13) _(R14) _(R15)           \
@@ -13,18 +12,4 @@ enum {
 #undef R
 };
 
-const char amd64_rnames[][6] = {
-#define R(r) #r,
-   LIST_REGS(R)
-#undef R
-};
-
-const struct mctarg t_amd64_sysv = {
-   .gpr0 = RAX, .ngpr = R15 - RAX + 1,
-   .fpr0 = XMM0, .nfpr = XMM15 - XMM0 + 1,
-   .rcallee = {{1<<RBX | 1<<R12 | 1<<R13 | 1<<R14 | 1<<R15}},
-   .rglob = {{1<<RSP | 1<<RBP}},
-   .rnames = amd64_rnames,
-};
-
 /* vim:set ts=3 sw=3 expandtab: */
diff --git a/amd64/sysv.c b/amd64/sysv.c
index e998036..55739e8 100644
--- a/amd64/sysv.c
+++ b/amd64/sysv.c
@@ -1,3 +1,106 @@
 #include "all.h"
 
+static int
+classify(uchar cls[2], const struct typedata *td, uint off)
+{
+   uint siz = alignup(td->siz, 8);
+   if (siz > 16) /* MEMORY */
+      return 0;
+   for (int i = 0; i < td->nmemb; ++i) {
+      struct fielddata *fld = &td->fld[i].f;
+      uint align = typealign(fld->t);
+      if (alignup(fld->off, align) != fld->off) /* unaligned field */
+         return cls[0] = cls[1] = 0;
+      if (isagg(fld->t)) {
+         if (!classify(cls, &typedata[fld->t.dat], fld->off))
+            return cls[0] = cls[1] = 0;
+      } else if (isflt(fld->t)) { /* SSE */
+         if (!cls[(fld->off + off)/8])
+            cls[(fld->off + off)/8] = KF8;
+      } else { /* INTEGER */
+         cls[(fld->off +  off)/8] = KI8;
+      }
+   }
+   return !!cls[0] + !!cls[1];
+}
+
+static int
+argabi(short r[2], uchar cls[2], int *ni, int *nf, union irtype typ)
+{
+   static const uchar intregs[] = { RDI, RSI, RDX, RCX, R8, R9 };
+   enum { NINT = arraylength(intregs), NFLT = 8 };
+   int ret, ni_save, nf_save;
+
+   if (!typ.isagg) {
+      if (kisflt(typ.cls) && *nf < NFLT) {
+         cls[0] = KF8; /* SSE */
+         r[0] = XMM0 + (*nf)++;
+         return 1;
+      }
+      if (*ni < NINT) {
+         cls[0] = KI8; /* INTEGER */
+         r[0] = intregs[(*ni)++];
+         return 1;
+      }
+      return 0; /* MEMORY */
+   }
+   cls[0] = cls[1] = 0;
+   ret = classify(cls, &typedata[typ.dat], 0);
+   if (!ret) return 0;
+   ni_save = *ni, nf_save = *nf;
+   assert(ret <= 2);
+   for (int i = 0; i < ret; ++i) {
+      assert(cls[i]);
+      if (cls[i] == KF8 && *nf < NFLT)
+         r[i] = XMM0 + (*nf)++;
+      else if (cls[i] == KI8 && *ni < NINT)
+         r[i] = intregs[(*ni)++];
+      else { /* MEMORY */
+         *ni = ni_save, *nf = nf_save;
+         return cls[0] = cls[1] = 0;
+      }
+   }
+   return ret;
+}
+
+static int
+retabi(short r[2], uchar cls[2], union irtype typ)
+{
+   int ret;
+
+   if (!typ.isagg) return kisflt(typ.cls) ? XMM0 : RAX;
+   cls[0] = cls[1] = 0;
+   ret = classify(cls, &typedata[typ.dat], 0);
+   if (!ret) { /* MEMORY */
+      r[0] = RDI; /* register for caller-owned result location argument */
+      return 0;
+   }
+   assert(ret <= 2);
+   for (int i = 0; i < ret; ++i) {
+      assert(cls[i]);
+      if (cls[i] == KF8) /* SSE (XMM0, XMM1) */
+         r[i] = XMM0 + i;
+      else if (cls[i] == KI8) /* INTEGER (RAX, RDX) */
+         r[i] = i == 0 ? RAX : RDX;
+      else assert(0);
+   }
+   return ret;
+}
+
+const char amd64_rnames[][6] = {
+#define R(r) #r,
+   LIST_REGS(R)
+#undef R
+};
+
+const struct mctarg t_amd64_sysv = {
+   .gpr0 = RAX, .ngpr = R15 - RAX + 1,
+   .fpr0 = XMM0, .nfpr = XMM15 - XMM0 + 1,
+   .rcallee = {{1<<RBX | 1<<R12 | 1<<R13 | 1<<R14 | 1<<R15}},
+   .rglob = {{1<<RSP | 1<<RBP}},
+   .rnames = amd64_rnames,
+   .abi_argregs = argabi,
+   .abi_retregs = retabi,
+};
+
 /* vim:set ts=3 sw=3 expandtab: */
-- 
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