Add auto-NOP insertion to work around flow-of-control PICA errata

source/picasso.h

@@ -62,6 +62,7 @@ enum
 //-----------------------------------------------------------------------------
 
 // Output buffer
+#define MAX_VSH_SIZE 512
 typedef std::vector<u32> outputBufType;
 typedef outputBufType::iterator outputBufIter;
 extern outputBufType g_outputBuf;
@@ -142,6 +143,8 @@ extern labelTableType g_labels;
 extern relocTableType g_labelRelocTable;
 extern aliasTableType g_aliases;
 
+extern bool g_autoNop;
+
 int AssembleString(char* str, const char* initialFilename);
 int RelocateProduct(void);
 

source/picasso_assembler.cpp

@@ -6,6 +6,7 @@
 
 static const char* curFile = NULL;
 static int curLine = -1;
+static bool lastWasEnd = false;
 
 std::vector<u32> g_outputBuf;
 
@@ -23,6 +24,8 @@ std::vector<Constant> g_constArray;
 int g_constArraySize = -1;
 const char* g_constArrayName;
 
+bool g_autoNop = true;
+
 class UniformAlloc
 {
 	int start, end, bound, tend;
@@ -795,6 +798,14 @@ static inline bool isBadInputRegCombination(int a, int b, int c)
 	return isBadInputRegCombination(a,b) || isBadInputRegCombination(b,c) || isBadInputRegCombination(c,a);
 }
 
+static void insertPaddingNop()
+{
+	if (g_autoNop)
+		BUF.push_back(FMT_OPCODE(MAESTRO_NOP));
+	else
+		fprintf(stderr, "%s:%d: warning: a padding NOP is required here\n", curFile, curLine);
+}
+
 DEF_COMMAND(format0)
 {
 	ENSURE_NO_MORE_ARGS();
@@ -1245,6 +1256,21 @@ DEF_DIRECTIVE(else)
 	if (elem.uExtra)
 		return throwError("spurious .else\n");
 
+	// Automatically add padding NOPs when necessary
+	if (lastWasEnd)
+	{
+		insertPaddingNop();
+		lastWasEnd = false;
+	} else
+	{
+		u32 p = BUF.size();
+		u32 lastOpcode = BUF[p-1] >> 26;
+		if (lastOpcode == MAESTRO_JMPC || lastOpcode == MAESTRO_JMPU
+			|| lastOpcode == MAESTRO_CALL || lastOpcode == MAESTRO_CALLC || lastOpcode == MAESTRO_CALLU
+			|| (p - elem.pos) < 2)
+			insertPaddingNop();
+	}
+
 	u32 curPos = BUF.size();
 	elem.uExtra = curPos;
 	u32& inst = BUF[elem.pos];
@@ -1265,6 +1291,24 @@ DEF_DIRECTIVE(end)
 		return throwError(".end with unmatched block\n");
 	
 	StackEntry& elem = g_stack[--g_stackPos];
+
+	// Automatically add padding NOPs when necessary
+	if (elem.type != SE_ARRAY && lastWasEnd)
+	{
+		insertPaddingNop();
+		lastWasEnd = false;
+	}
+	else if (elem.type == SE_PROC || elem.type == SE_FOR || elem.type == SE_IF && BUF.size() > 0)
+	{
+		u32 p = BUF.size();
+		u32 lastOpcode = BUF[p-1] >> 26;
+		if (lastOpcode == MAESTRO_JMPC || lastOpcode == MAESTRO_JMPU
+			|| lastOpcode == MAESTRO_CALL || lastOpcode == MAESTRO_CALLC || lastOpcode == MAESTRO_CALLU
+			|| (elem.type == SE_FOR && lastOpcode == MAESTRO_BREAKC)
+			|| (elem.type != SE_ARRAY && (p - elem.pos) < (elem.type != SE_PROC ? 2 : 1)))
+			insertPaddingNop();
+	}
+
 	u32 curPos = BUF.size();
 	u32 size = curPos - elem.pos;
 
@@ -1287,6 +1331,7 @@ DEF_DIRECTIVE(end)
 			u32& inst = BUF[elem.pos];
 			inst &= ~(0xFFF << 10);
 			inst |= (curPos-1) << 10;
+			lastWasEnd = true;
 			break;
 		}
 
@@ -1307,6 +1352,7 @@ DEF_DIRECTIVE(end)
 				inst &= ~0x3FF;
 				inst |= curPos - elem.uExtra;
 			}
+			lastWasEnd = true;
 			break;
 		}
 
@@ -1814,6 +1860,12 @@ int ProcessCommand(const char* cmd)
 		table = dirTable;
 	} else if (!g_stackPos)
 		return throwError("instruction outside block\n");
+	else
+	{
+		lastWasEnd = false;
+		if (!GetDvleData()->isGeoShader && g_outputBuf.size() >= MAX_VSH_SIZE)
+			return throwError("instruction outside vertex shader code memory (max %d instructions, currently %d)\n", MAX_VSH_SIZE, g_outputBuf.size());
+	}
 
 	for (int i = 0; table[i].name; i ++)
 		if (stricmp(table[i].name, cmd) == 0)

source/picasso_frontend.cpp

@@ -36,6 +36,7 @@ int usage(const char* prog)
 		"Options:\n"
 		"  -o, --out=<file>        Specifies the name of the SHBIN file to generate\n"
 		"  -h, --header=<file>     Specifies the name of the header file to generate\n"
+		"  -n, --no-nop            Disables the automatic insertion of padding NOPs\n"
 		"  -v, --version           Displays version information\n"
 		, prog);
 	return EXIT_FAILURE;
@@ -50,18 +51,20 @@ int main(int argc, char* argv[])
 		{ "out",    required_argument, NULL, 'o' },
 		{ "header", required_argument, NULL, 'h' },
 		{ "help",   no_argument,       NULL, '?' },
+		{ "no-nop", no_argument,       NULL, 'n' },
 		{ "version",no_argument,       NULL, 'v' },
 		{ NULL, 0, NULL, 0 }
 	};
 
 	int opt, optidx = 0;
-	while ((opt = getopt_long(argc, argv, "o:h:?v", long_options, &optidx)) != -1)
+	while ((opt = getopt_long(argc, argv, "o:h:?nv", long_options, &optidx)) != -1)
 	{
 		switch (opt)
 		{
 			case 'o': shbinFile = optarg; break;
 			case 'h': hFile     = optarg; break;
-			case '?':        usage(argv[0]); return EXIT_SUCCESS;
+			case '?': usage(argv[0]); return EXIT_SUCCESS;
+			case 'n': g_autoNop = false; break;
 			case 'v': printf("%s - Built on %s %s\n", PACKAGE_STRING, __DATE__, __TIME__); return EXIT_SUCCESS;
 			default:  return usage(argv[0]);
 		}