* tests/assemble.test: Added more "white box" tests.

* generic/tclAssembly.c: Added the error checking and reporting
for undefined labels. Revised code so that no pointers into the
bytecode sequence are held (because the sequence can move!),
that no Tcl_HashEntry pointers are held (because the hash table
doesn't guarantee their stability!) and to eliminate the BBHash
table, which is merely additional information indexed by jump
labels and can just as easily be held in the 'label' structure.
Renamed shared structures to CamelCase, and renamed 'label' to
JumpLabel because other types of labels may eventually be possible.

1 files changed, 63 insertions, 19 deletions

diff --git a/generic/tclAssembly.h b/generic/tclAssembly.h
index c1cb0e5..6ea9137 100644
--- a/generic/tclAssembly.h
+++ b/generic/tclAssembly.h
@@ -3,12 +3,20 @@
 
 #include "tclCompile.h"
 
+/* 
+ * Structure that defines a basic block - a linear sequence of bytecode
+ * instructions with no jumps in or out.
+ */
+
 typedef struct BasicBlock {
-    /* FIXME: start needs to be an offset from envPtr->codeStart */
-    unsigned char * start;	/* Instruction address of the start
-				 * of the block */
-    int startLine;		/* Index in the input instruction
-				 * list of the start of the block */
+
+    int startOffset;		/* Instruction offset of the start of 
+				 * the block */
+    int startLine;		/* Line number in the input script of the
+				 * instruction at the  start of the block */
+    int jumpLine;	        /* Line number in the input script of the
+				 * 'jump' instruction that ends the block,
+				 * or -1 if there is no jump */
     int may_fall_thru;      	/* Flag == 1 if control passes from this
 				 * block to its successor. */
     int visited;		/* Flag==1 if this block has been visited
@@ -21,8 +29,7 @@ typedef struct BasicBlock {
 				 * block:  NULL at the end of the bytecode 
 				 * sequence or if the block ends in an
 				 * unconditional jump */ 
-    Tcl_HashEntry * jumpTargetLabelHashEntry;
-				/* Jump target label if the jump target 
+    Tcl_Obj * jumpTarget;	/* Jump target label if the jump target 
 				 * is unresolved */
     
     int initialStackDepth;	/* Absolute stack depth on entry */
@@ -32,7 +39,9 @@ typedef struct BasicBlock {
 
 } BasicBlock;
 
-typedef enum talInstType {
+/* Source instruction type recognized by the assembler */
+
+typedef enum TalInstType {
 
     ASSEM_1BYTE,    /* The instructions that are directly mapped to tclInstructionTable in tclCompile.c*/
     ASSEM_BOOL,	    /* One Boolean operand */
@@ -54,21 +63,56 @@ typedef enum talInstType {
     ASSEM_PUSH,     /* These instructions will be looked up from talInstructionTable */
     ASSEM_REVERSE,  /* REVERSE: consumes n operands and produces n */
     ASSEM_SINT1,    /* One 1-byte signed-integer operand (INCR_STK_IMM) */
-} talInstType;
+} TalInstType;
 
-typedef struct talInstDesc {
+/* Description of an instruction recognized by the assembler. */
+
+typedef struct TalInstDesc {
     const char *name;		/* Name of instruction. */
-    talInstType instType; 	/* The type of instruction */
-    int tclInstCode;
-    int operandsConsumed;
-    int operandsProduced;
+    TalInstType instType; 	/* The type of instruction */
+    int tclInstCode;		/* Instruction code. For instructions having
+				 * 1- and 4-byte variables, tclInstCode is
+				 * ((1byte)<<8) || (4byte) */
+    int operandsConsumed;	/* Number of operands consumed by the
+				 * operation, or INT_MIN if the operation
+				 * is variadic */
+    int operandsProduced;	/* Number of operands produced by the
+				 * operation. If negative, the operation
+				 * has a net stack effect of 
+				 * -1-operandsProduced */
+} TalInstDesc;
+
+/* Description of a label in the assembly code */
+
+typedef struct JumpLabel {
+    int isDefined;		/* Flag == 1 if label is defined */
+    int offset;			/* Offset in the code where the label starts,
+				 * or head of a linked list of jump target
+				 * addresses if the label is undefined */
+    BasicBlock* basicBlock;	/* Basic block that begins at the label */
+} JumpLabel;
+
+/* Structure that holds the state of the assembler while generating code */
+
+typedef struct AssembleEnv {
+    CompileEnv* envPtr;		/* Compilation environment being used
+				 * for code generation */
+    Tcl_Parse* parsePtr;        /* Parse of the current line of source */
+    Tcl_HashTable labelHash;	/* Hash table whose keys are labels and
+				 * whose values are 'label' objects storing 
+				 * the code offsets of the labels. */
+
+    int cmdLine;		/* Current line number within the assembly 
+				 * code */
+    int* clNext;		/* Invisible continuation line for
+				 * [info frame] */
 
-} talInstDesc;
+    BasicBlock* head_bb;	/* First basic block in the code */
+    BasicBlock* curr_bb;	/* Current basic block */
 
-typedef struct label {
-    int isDefined;
-    int offset;    
-} label;
+    int maxDepth;	     	/* Maximum stack depth encountered */
+    int flags;			/* Compilation flags (TCL_EVAL_DIRECT) */
+} AssembleEnv;
 
 MODULE_SCOPE int TclAssembleCode(CompileEnv* compEnv, const char* codePtr,
 				 int codeLen, int flags);