Fix inverted sc return code (argh) and lr/sc tests which also assumed the sc code was inverted

hdl/hazard3_core.v

@@ -1036,7 +1036,8 @@ always @ (*) begin
 		m_result = bus_rdata_d;
 	end else if (|EXTENSION_A && xm_memop == MEMOP_SC_W) begin
 		// sc.w may fail due to negative response from either local or global monitor.
-		m_result = {31'h0, mw_local_exclusive_reserved && bus_dph_exokay_d};
+		// Note the polarity of the result: 0 for success, 1 for failure.
+		m_result = {31'h0, !(mw_local_exclusive_reserved && bus_dph_exokay_d)};
 	end else if (xm_memop != MEMOP_NONE && xm_memop != MEMOP_AMO) begin
 		m_result = m_rdata_pick_sext;
 	end else if (MUL_FAST && m_fast_mul_result_vld) begin

test/sim/sw_testcases/lr_sc_bypass.c

@@ -7,9 +7,9 @@
 /*EXPECTED-OUTPUT***************************************************************
 
 lr -> mv: 12345678
-lr -> sc: sc returned 1
+lr -> sc: sc returned 0
 scratch[1] = deadbeef
-sc -> mv: sc returned 0
+sc -> mv: sc returned 1
 scratch[0] = 5678a5a5
 
 *******************************************************************************/

test/sim/sw_testcases/lr_sc_fault.c

@@ -9,13 +9,13 @@
 Failed load, suppressed store
 -> exception, mcause = 5
 exception instr: 100627af
-sc.w result: 0
+sc.w result: 1
 Good load, failed store
 -> exception, mcause = 7
 exception instr: 18a5a52f
 sc.w result: 123
 Repeated failed store
-sc.w result: 0
+sc.w result: 1
 
 *******************************************************************************/
 
@@ -42,7 +42,7 @@ int main() {
 	// suppressing the sc.w.
 	tb_puts("Failed load, suppressed store\n");
 	sc_result = do_lr_sc(123, bad_addr, bad_addr);
-	// Failing sc.w must write 0 to the success register.
+	// Failing sc.w must write 1 to the success register.
 	tb_printf("sc.w result: %u\n", sc_result);
 
 	// This time the sc.w should fault, after the successful lr.w.
@@ -58,7 +58,7 @@ int main() {
 		"sc.w %0, zero, (%1)\n"
 		: "+r" (sc_result) : "r" (bad_addr)
 	);
-	// Failing sc.w must write 0 to result register.
+	// Failing sc.w must write 1 to result register.
 	tb_printf("sc.w result: %u\n", sc_result);
 
 	return 0;

test/sim/sw_testcases/lr_sc_smoke.c

@@ -17,7 +17,7 @@ OK
 volatile uint32_t scratch[2];
 
 int main() {
-	uint32_t load_result, success;
+	uint32_t load_result, sc_fail;
 	tb_puts("Test 1: lr.w -> nop -> sc.w\n");
 	scratch[0] = 0x1234;
 	asm volatile (
@@ -26,12 +26,12 @@ int main() {
 		"sc.w %1, %3, (%2)\n"
 		// Note the "&": this marks an "earlyclobber" operand, telling GCC it can't
 		// allocate this output to an input register. (particularly, %0 to %2)
-		: "=&r" (load_result), "=r" (success)
+		: "=&r" (load_result), "=r" (sc_fail)
 		: "r" (&scratch[0]), "r" (0x5678)
 	);
 	tb_assert(load_result == 0x1234, "Bad load result %08x\n", load_result);
 	tb_assert(scratch[0] == 0x5678, "Store didn't write memory\n");
-	tb_assert(success == 1, "Should report success\n");
+	tb_assert(sc_fail == 0, "Should report success\n");
 	tb_puts("OK\n");
 
 	tb_puts("Test 2: lr.w -> sc.w\n");
@@ -39,23 +39,23 @@ int main() {
 	asm volatile (
 		"lr.w %0, (%2)\n"
 		"sc.w %1, %3, (%2)\n"
-		: "=&r" (load_result), "=r" (success)
+		: "=&r" (load_result), "=r" (sc_fail)
 		: "r" (&scratch[0]), "r" (0xa5a5)
 	);
 	tb_assert(load_result == 0xabcd, "Bad load result %08x\n", load_result);
 	tb_assert(scratch[0] == 0xa5a5, "Store didn't write memory\n");
-	tb_assert(success == 1, "Should report success\n");
+	tb_assert(sc_fail == 0, "Should report success\n");
 	tb_puts("OK\n");
 
 	tb_puts("Test 3: sc.w with no preceding lr.w\n");
 	scratch[0] = 0x1234;
 	asm volatile (
 		"sc.w %0, %2, (%1)\n"
-		: "=r" (success)
+		: "=r" (sc_fail)
 		: "r" (&scratch[0]), "r" (0x5678)
 	);
 	tb_assert(scratch[0] == 0x1234, "Store shouldn't write memory\n");
-	tb_assert(success == 0, "Should report failure\n");
+	tb_assert(sc_fail == 1, "Should report failure\n");
 	tb_puts("OK\n");
 
 	// Reservation is only cleared by other harts' stores.
@@ -66,12 +66,12 @@ int main() {
 		"lr.w %0, (%2)\n"
 		"sw %3, 4(%2)\n"
 		"sc.w %1, %4, (%2)\n"
-		: "=&r" (load_result), "=r" (success)
+		: "=&r" (load_result), "=r" (sc_fail)
 		: "r" (&scratch[0]), "r" (0xabcd), "r" (0x5678)
 	);
 	tb_assert(scratch[1] == 0xabcd, "Regular store should succeed\n");
 	tb_assert(scratch[0] == 0x5678, "sc didn't write memory\n");
-	tb_assert(success == 1, "Should report success\n");
+	tb_assert(sc_fail == 0, "Should report success\n");
 	tb_puts("OK\n");
 
 	return 0;