[PATCH] Hexagon: add PC alignment check and exception

[Matheus Tavares Bernardino]

The Hexagon Programmer's Reference Manual says that the exception 0x1e
should be raised upon an unaligned program counter. Let's implement that
and also add tests for both the most common case as well as packets with
multiple change-of-flow instructions.

Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
---
 target/hexagon/cpu_bits.h                  |  1 +
 target/hexagon/translate.h                 |  2 ++
 target/hexagon/genptr.c                    | 21 ++++++++++++++++-----
 target/hexagon/translate.c                 |  2 +-
 tests/tcg/hexagon/Makefile.target          | 13 +++++++++++++
 tests/tcg/hexagon/unaligned_pc.S           | 10 ++++++++++
 tests/tcg/hexagon/unaligned_pc_multi_cof.S | 13 +++++++++++++
 7 files changed, 56 insertions(+), 6 deletions(-)
 create mode 100644 tests/tcg/hexagon/unaligned_pc.S
 create mode 100644 tests/tcg/hexagon/unaligned_pc_multi_cof.S

diff --git a/target/hexagon/cpu_bits.h b/target/hexagon/cpu_bits.h
index 96fef71729..d6900c8bda 100644
--- a/target/hexagon/cpu_bits.h
+++ b/target/hexagon/cpu_bits.h
@@ -23,6 +23,7 @@
 #define HEX_EXCP_FETCH_NO_UPAGE  0x012
 #define HEX_EXCP_INVALID_PACKET  0x015
 #define HEX_EXCP_INVALID_OPCODE  0x015
+#define HEX_EXCP_PC_NOT_ALIGNED  0x01e
 #define HEX_EXCP_PRIV_NO_UREAD   0x024
 #define HEX_EXCP_PRIV_NO_UWRITE  0x025
 
diff --git a/target/hexagon/translate.h b/target/hexagon/translate.h
index 4dd59c6726..daf11eb584 100644
--- a/target/hexagon/translate.h
+++ b/target/hexagon/translate.h
@@ -75,6 +75,8 @@ typedef struct DisasContext {
     TCGv dczero_addr;
 } DisasContext;
 
+void gen_exception_end_tb(DisasContext *ctx, int excp);
+
 static inline void ctx_log_pred_write(DisasContext *ctx, int pnum)
 {
     if (!test_bit(pnum, ctx->pregs_written)) {
diff --git a/target/hexagon/genptr.c b/target/hexagon/genptr.c
index dbae6c570a..c96edd9379 100644
--- a/target/hexagon/genptr.c
+++ b/target/hexagon/genptr.c
@@ -473,6 +473,7 @@ static void gen_write_new_pc_addr(DisasContext *ctx, TCGv 
addr,
                                   TCGCond cond, TCGv pred)
 {
     TCGLabel *pred_false = NULL;
+    TCGLabel *branch_taken = NULL;
     if (cond != TCG_COND_ALWAYS) {
         pred_false = gen_new_label();
         tcg_gen_brcondi_tl(cond, pred, 0, pred_false);
@@ -480,12 +481,22 @@ static void gen_write_new_pc_addr(DisasContext *ctx, TCGv 
addr,
 
     if (ctx->pkt->pkt_has_multi_cof) {
         /* If there are multiple branches in a packet, ignore the second one */
-        tcg_gen_movcond_tl(TCG_COND_NE, hex_gpr[HEX_REG_PC],
-                           ctx->branch_taken, tcg_constant_tl(0),
-                           hex_gpr[HEX_REG_PC], addr);
+        branch_taken = gen_new_label();
+        tcg_gen_brcondi_tl(TCG_COND_NE, ctx->branch_taken, 0, branch_taken);
         tcg_gen_movi_tl(ctx->branch_taken, 1);
-    } else {
-        tcg_gen_mov_tl(hex_gpr[HEX_REG_PC], addr);
+    }
+
+    TCGLabel *pc_aligned = gen_new_label();
+    TCGv pc_remainder = tcg_temp_new();
+    tcg_gen_andi_tl(pc_remainder, addr, PCALIGN_MASK);
+    tcg_gen_brcondi_tl(TCG_COND_EQ, pc_remainder, 0, pc_aligned);
+    gen_exception_end_tb(ctx, HEX_EXCP_PC_NOT_ALIGNED);
+    gen_set_label(pc_aligned);
+
+    tcg_gen_mov_tl(hex_gpr[HEX_REG_PC], addr);
+
+    if (ctx->pkt->pkt_has_multi_cof) {
+        gen_set_label(branch_taken);
     }
 
     if (cond != TCG_COND_ALWAYS) {
diff --git a/target/hexagon/translate.c b/target/hexagon/translate.c
index f163eefe97..e6ee63a53e 100644
--- a/target/hexagon/translate.c
+++ b/target/hexagon/translate.c
@@ -185,7 +185,7 @@ static void gen_end_tb(DisasContext *ctx)
     ctx->base.is_jmp = DISAS_NORETURN;
 }
 
-static void gen_exception_end_tb(DisasContext *ctx, int excp)
+void gen_exception_end_tb(DisasContext *ctx, int excp)
 {
     gen_exec_counters(ctx);
     tcg_gen_movi_tl(hex_gpr[HEX_REG_PC], ctx->next_PC);
diff --git a/tests/tcg/hexagon/Makefile.target 
b/tests/tcg/hexagon/Makefile.target
index f839b2c0d5..02d7fff34c 100644
--- a/tests/tcg/hexagon/Makefile.target
+++ b/tests/tcg/hexagon/Makefile.target
@@ -51,6 +51,19 @@ HEX_TESTS += scatter_gather
 HEX_TESTS += hvx_misc
 HEX_TESTS += hvx_histogram
 HEX_TESTS += invalid-slots
+HEX_TESTS += unaligned_pc
+HEX_TESTS += unaligned_pc_multi_cof
+
+run-unaligned_pc: unaligned_pc
+run-unaligned_pc_multi_cof: unaligned_pc_multi_cof
+run-unaligned_pc run-unaligned_pc_multi_cof:
+       $(call run-test, $<, $(QEMU) $< 2> $<.stderr,"$< on $(TARGET_NAME)"); \
+       if [ $$? -ne 1 ] ; then \
+               return 1; \
+       fi
+       $(call quiet-command, \
+               grep -q "exception 0x1e" $<.stderr, \
+               "GREP", "exception 0x1e");
 
 run-and-check-exception = $(call run-test,$2,$3 2>$2.stderr; \
        test $$? -eq 1 && grep -q "exception $(strip $1)" $2.stderr)
diff --git a/tests/tcg/hexagon/unaligned_pc.S b/tests/tcg/hexagon/unaligned_pc.S
new file mode 100644
index 0000000000..39d6b2060b
--- /dev/null
+++ b/tests/tcg/hexagon/unaligned_pc.S
@@ -0,0 +1,10 @@
+test:
+       allocframe(#0x8)
+       r0 = #0xffffffff
+       framekey = r0
+       dealloc_return
+
+.global _start
+_start:
+       call test
+       jump pass
diff --git a/tests/tcg/hexagon/unaligned_pc_multi_cof.S 
b/tests/tcg/hexagon/unaligned_pc_multi_cof.S
new file mode 100644
index 0000000000..a83e248ece
--- /dev/null
+++ b/tests/tcg/hexagon/unaligned_pc_multi_cof.S
@@ -0,0 +1,13 @@
+.org 0x3
+test:
+       nop
+       jumpr r31
+
+.global _start
+_start:
+       p0 = cmp.eq(r0, r0)
+       {
+               if (p0) jump test
+               jump pass
+       }
+       jump pass
-- 
2.37.2