From 142d509af22cc51f08aa5bdb8bea96f5e088a3ef Mon Sep 17 00:00:00 2001
From: Walter Bright <WalterBright@users.noreply.github.com>
Date: Sat, 15 Mar 2025 01:27:52 -0700
Subject: [PATCH] get branches to block working (#20996)

* carith() function in exe1.c tests

* get branches to blocks working
---
 compiler/src/dmd/backend/arm/cod3.d  | 18 +++++++++++++-----
 compiler/src/dmd/backend/arm/cod4.d  | 11 ++++++-----
 compiler/src/dmd/backend/arm/instr.d | 10 +++++++++-
 compiler/src/dmd/backend/x86/cod3.d  |  7 ++++++-
 4 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/compiler/src/dmd/backend/arm/cod3.d b/compiler/src/dmd/backend/arm/cod3.d
index 9be9a0151d..d76484e31d 100644
--- a/compiler/src/dmd/backend/arm/cod3.d
+++ b/compiler/src/dmd/backend/arm/cod3.d
@@ -292,7 +292,7 @@ void gen_loadcse(ref CodeBuilder cdb, tym_t tym, reg_t reg, size_t slot)
 void genBranch(ref CodeBuilder cdb, COND cond, FL fltarg, block* targ)
 {
     code cs;
-    cs.Iop = ((0x54 << 24) | cond);
+    cs.Iop = INSTR.b_cond(0, cond);     // offset is 0 for now, fix in codout()
     cs.Iflags = 0;
     cs.IFL1 = fltarg;                   // FL.block (or FL.code)
     cs.IEV1.Vblock = targ;              // target block (or code)
@@ -741,6 +741,7 @@ Lret:
 @trusted
 int branch(block* bl,int flag)
 {
+    //printf("branch() flag: %d\n", flag);
     int bytesaved;
     code* c,cn,ct;
     targ_size_t offset,disp;
@@ -1491,6 +1492,7 @@ printf("offset: %lld localsize: %lld REGSIZE*2: %d\n", offset, localsize, REGSIZ
             case FL.func:
             case FL.code:
             case FL.unde:
+            case FL.block:
                 break;
 
             default:
@@ -1523,7 +1525,8 @@ void jmpaddr(code* c)
     while (c)
     {
         const op = c.Iop;
-        if (isBranch(op)) // or CALL?
+        //printf("%08X ", c.Iop); disassemble(c.Iop);
+        if (isBranch(op) && c.IFL2 == FL.code) // or CALL?
         {
             ci = code_next(c);
             ctarg = c.IEV1.Vcode;  /* target code                  */
@@ -1678,9 +1681,14 @@ uint codout(int seg, code* c, Barray!ubyte* disasmBuf, ref targ_size_t framehand
         if (ggen.available() < 4)
             ggen.flush();
 
-        //printf("op: %08x\n", op);
-        //if ((op & 0xFC00_0000) == 0x9400_0000) // BL <label>
-        if (Symbol* s = c.IEV1.Vsym)
+        if (c.IFL1 == FL.block)  // branch to a block - compute offset
+        {
+            ggen.flush();
+            int ad = cast(int)(c.IEV1.Vblock.Boffset - ggen.offset);
+            op |= ((ad >> 2) & 0x7FFFF) << 5; // imm19 in opcode
+            ggen.gen32(op);
+        }
+        else if (Symbol* s = c.IEV1.Vsym)
         {
             switch (s.Sclass)
             {
diff --git a/compiler/src/dmd/backend/arm/cod4.d b/compiler/src/dmd/backend/arm/cod4.d
index 4d0a7c6e71..ff387847a8 100644
--- a/compiler/src/dmd/backend/arm/cod4.d
+++ b/compiler/src/dmd/backend/arm/cod4.d
@@ -608,7 +608,7 @@ void cdmulass(ref CGstate cg, ref CodeBuilder cdb,elem* e,ref regm_t pretregs)
     regm_t earegm = mask(cs.base) | mask(cs.index);
     regm_t retregs;
     reg_t reg;
-    if (cs.reg)
+    if (cs.reg != NOREG)
     {
         reg = cs.reg;
         retregs = mask(reg);
@@ -759,7 +759,7 @@ void cdshass(ref CGstate cg, ref CodeBuilder cdb,elem* e,ref regm_t pretregs)
     regm_t earegm = mask(cs.base) | mask(cs.index);
     regm_t retregs;
     reg_t Rshiftee;
-    if (cs.reg)
+    if (cs.reg != NOREG)
     {
         Rshiftee = cs.reg;
         retregs = mask(Rshiftee);
@@ -793,11 +793,12 @@ void cdshass(ref CGstate cg, ref CodeBuilder cdb,elem* e,ref regm_t pretregs)
     uint opcode;
     switch (e.Eoper)
     {
-        case OPshl:     opcode = 0x8;   break;
-        case OPshr:     opcode = 0x9;   break;
-        case OPashr:    opcode = 0xA;   break;
+        case OPshlass:  opcode = 0x8;   break;
+        case OPshrass:  opcode = 0x9;   break;
+        case OPashrass: opcode = 0xA;   break;
         //case OPror:     opcode = 0xB;   break;
         default:
+            elem_print(e);
             assert(0);
     }
 
diff --git a/compiler/src/dmd/backend/arm/instr.d b/compiler/src/dmd/backend/arm/instr.d
index 1469689a1b..4fdeef0701 100644
--- a/compiler/src/dmd/backend/arm/instr.d
+++ b/compiler/src/dmd/backend/arm/instr.d
@@ -264,7 +264,15 @@ struct INSTR
     /* https://www.scs.stanford.edu/~zyedidia/arm64/encodingindex.html#control                          */
 
     /* Conditional branch (immediate)
-     * Miscellaneous branch (immediate)
+     * B.<cond> <label> https://www.scs.stanford.edu/~zyedidia/arm64/b_cond.html
+     */
+    static uint b_cond(int imm19, uint cond) { return (0x54 << 24) | ((imm19 & 0x7FFFF) << 5) | cond; }
+
+    /* BC.<cond> <label> https://www.scs.stanford.edu/~zyedidia/arm64/bc_cond.html
+     */
+    static uint bc_cond(int imm19, uint cond) { return (0x54 << 24) | (1 << 4) | ((imm19 & 0x7FFFF) << 5) | cond; }
+
+    /* Miscellaneous branch (immediate)
      */
 
     /* Exception generation http://www.scs.stanford.edu/~zyedidia/arm64/encodingindex.html#exception
diff --git a/compiler/src/dmd/backend/x86/cod3.d b/compiler/src/dmd/backend/x86/cod3.d
index 3564b8e1d0..7ecf604eab 100644
--- a/compiler/src/dmd/backend/x86/cod3.d
+++ b/compiler/src/dmd/backend/x86/cod3.d
@@ -886,6 +886,8 @@ private code* callFinallyBlock(block* bf, regm_t retregs)
 @trusted
 void outblkexitcode(ref CodeBuilder cdb, block* bl, ref int anyspill, const(FL)* sflsave, Symbol** retsym, const regm_t mfuncregsave)
 {
+    //printf("outblkexitcode()\n");
+    bool AArch64 = cgstate.AArch64;
     CodeBuilder cdb2; cdb2.ctor();
     elem* e = bl.Belem;
     block* nextb;
@@ -923,7 +925,10 @@ void outblkexitcode(ref CodeBuilder cdb, block* bl, ref int anyspill, const(FL)*
             if (nextb != bl.Bnext)
             {
                 assert(!(bl.Bflags & BFL.epilog));
-                genjmp(cdb,JMP,FL.block,nextb);
+                if (AArch64)
+                    dmd.backend.arm.cod3.genBranch(cdb,COND.al,FL.block,nextb);
+                else
+                    genjmp(cdb,JMP,FL.block,nextb);
             }
             break;