From c82e52d55bd31eea943c616ad780f27e5ab9dc7a Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Tue, 28 Jun 2016 15:11:06 +0200
Subject: [PATCH] tccasm: Implement .pushsection and .popsection

---
 tcc.h           |  4 ++--
 tccasm.c        | 27 ++++++++++++++++++++++++++-
 tcctok.h        |  2 ++
 tests/asmtest.S | 10 ++++++++++
 4 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/tcc.h b/tcc.h
index 1e2b815..4de48e7 100644
--- a/tcc.h
+++ b/tcc.h
@@ -448,8 +448,8 @@ typedef struct Section {
     int nb_hashed_syms;      /* used to resize the hash table */
     struct Section *link;    /* link to another section */
     struct Section *reloc;   /* corresponding section for relocation, if any */
-    struct Section *hash;     /* hash table for symbols */
-    struct Section *next;
+    struct Section *hash;    /* hash table for symbols */
+    struct Section *prev;    /* previous section on section stack */
     char name[1];           /* section name */
 } Section;
 
diff --git a/tccasm.c b/tccasm.c
index 50fb794..ee14073 100644
--- a/tccasm.c
+++ b/tccasm.c
@@ -335,6 +335,22 @@ static void use_section(TCCState *s1, const char *name)
     use_section1(s1, sec);
 }
 
+static void push_section(TCCState *s1, const char *name)
+{
+    Section *sec = find_section(s1, name);
+    sec->prev = cur_text_section;
+    use_section1(s1, sec);
+}
+
+static void pop_section(TCCState *s1)
+{
+    Section *prev = cur_text_section->prev;
+    if (!prev)
+        tcc_error(".popsection without .pushsection");
+    cur_text_section->prev = NULL;
+    use_section1(s1, prev);
+}
+
 static void asm_parse_directive(TCCState *s1)
 {
     int n, offset, v, size, tok1;
@@ -683,10 +699,12 @@ static void asm_parse_directive(TCCState *s1)
             next();
         }
         break;
+    case TOK_ASMDIR_pushsection:
     case TOK_ASMDIR_section:
         {
             char sname[256];
 
+	    tok1 = tok;
             /* XXX: support more options */
             next();
             sname[0] = '\0';
@@ -711,7 +729,10 @@ static void asm_parse_directive(TCCState *s1)
                 }
             }
             last_text_section = cur_text_section;
-            use_section(s1, sname);
+	    if (tok1 == TOK_ASMDIR_section)
+	        use_section(s1, sname);
+	    else
+	        push_section(s1, sname);
         }
         break;
     case TOK_ASMDIR_previous:
@@ -725,6 +746,10 @@ static void asm_parse_directive(TCCState *s1)
             last_text_section = sec;
         }
         break;
+    case TOK_ASMDIR_popsection:
+	next();
+	pop_section(s1);
+	break;
 #ifdef TCC_TARGET_I386
     case TOK_ASMDIR_code16:
         {
diff --git a/tcctok.h b/tcctok.h
index 7480ac7..6e2a041 100644
--- a/tcctok.h
+++ b/tcctok.h
@@ -323,6 +323,8 @@
  DEF_ASMDIR(data)
  DEF_ASMDIR(bss)
  DEF_ASMDIR(previous)
+ DEF_ASMDIR(pushsection)
+ DEF_ASMDIR(popsection)
  DEF_ASMDIR(fill)
  DEF_ASMDIR(rept)
  DEF_ASMDIR(endr)
diff --git a/tests/asmtest.S b/tests/asmtest.S
index 2e634af..2518510 100644
--- a/tests/asmtest.S
+++ b/tests/asmtest.S
@@ -717,6 +717,16 @@ ft1: ft2: ft3: ft4: ft5: ft6: ft7: ft8: ft9:
 .endr
 .fill 4,1,0x90
 
+.section .text.one,"ax"
+nop
+.previous
+.pushsection .text.one,"ax"
+nop
+.pushsection .text.two,"ax"
+nop
+.popsection
+.popsection
+
     movd %esi, %mm1
     movd %edi, %xmm2
     movd (%ebx), %mm3