s390x: Fix IR generation for SRNMB

disasm-test generated this test:

  asm volatile("srnmb 4095(%r0)");

which was disassembled in VEX to

  srnmb 0

causing a mismatch with what objdump does.

4095 is not a valid bfp rounding mode and the old implementation of
s390_irgen_SRNMB let it slide by with a warning. However, POP calls for a
specification exception in this case. This is what this patch changes.i
It also eliminates the s390_irgen_srnmb_wrapper function along the way.

While adjusting none/tests/s390x/srnmb.* I noticed that the line
number shown in the specification exception is incorrect. This
is not a regression. It has been incorrect before as well.

I have opened https://bugs.kde.org/show_bug.cgi?id=502729 fro the line
number issue.

diff --git a/VEX/priv/guest_s390_toIR.c b/VEX/priv/guest_s390_toIR.c
index 63dc360b0f0e8a26b09eece1a25e65e261ab569f..5381e417e8c7950c4b94b599d38c69cdd8f1ecfc 100644 (file)
--- a/VEX/priv/guest_s390_toIR.c
+++ b/VEX/priv/guest_s390_toIR.c
@@ -11313,12 +11313,24 @@ s390_irgen_SRNM(IRTemp op2addr)
 }
 
 static const HChar *
-s390_irgen_SRNMB(IRTemp op2addr)
+s390_irgen_SRNMB(UChar b2, UShort d2)
 {
-   UInt input_mask, fpc_mask;
+   /* Can only check at IR generation time when b2 == 0 */
+   if (b2 == 0) {
+      s390_insn_assert("srnmb", d2 <= 3 || d2 == 7);  // valid rounding mode
+      /* d2 == 7 requires fpext */
+      if (d2 == 7 && ! s390_host_has_fpext) {
+         emulation_failure(EmFail_S390X_fpext);
+         return "srnmb";
+      }
+   }
+   IRTemp op2addr = newTemp(Ity_I64);
 
-   input_mask = 7;
-   fpc_mask = 7;
+   assign(op2addr, binop(Iop_Add64, mkU64(d2), b2 != 0 ? get_gpr_dw0(b2) :
+          mkU64(0)));
+
+   UInt input_mask = 7;
+   UInt fpc_mask = 7;
 
    put_fpc_w0(binop(Iop_Or32,
                     binop(Iop_And32, get_fpc_w0(), mkU32(~fpc_mask)),
@@ -11327,25 +11339,8 @@ s390_irgen_SRNMB(IRTemp op2addr)
    return "srnmb";
 }
 
-static void
-s390_irgen_srnmb_wrapper(UChar b2, UShort d2)
-{
-   if (b2 == 0) {  /* This is the typical case */
-      if (d2 > 3) {
-         if (s390_host_has_fpext && d2 == 7) {
-            /* ok */
-         } else {
-            emulation_warning(EmWarn_S390X_invalid_rounding);
-            d2 = S390_FPC_BFP_ROUND_NEAREST_EVEN;
-         }
-      }
-   }
-
-   s390_format_S_RD(s390_irgen_SRNMB, b2, d2);
-}
 
-/* Wrapper to validate the parameter as in SRNMB is not required, as all
-   the 8 values in op2addr[61:63] correspond to a valid DFP rounding mode */
+/* All 8 values in op2addr[61:63] correspond to a valid DFP rounding mode */
 static const HChar *
 s390_irgen_SRNMT(IRTemp op2addr)
 {
@@ -21017,7 +21012,7 @@ s390_decode_4byte_and_irgen(const UChar *bytes)
                                  goto ok;
    case 0xb2b1: /* STFL */ goto unimplemented;
    case 0xb2b2: /* LPSWE */ goto unimplemented;
-   case 0xb2b8: s390_irgen_srnmb_wrapper(S_b2(ovl), S_d2(ovl));
+   case 0xb2b8: s390_format_S_RD_raw(s390_irgen_SRNMB, S_b2(ovl), S_d2(ovl));
       goto ok;
    case 0xb2b9: s390_format_S_RD(s390_irgen_SRNMT, S_b2(ovl), S_d2(ovl));
       goto ok;

diff --git a/VEX/priv/main_main.c b/VEX/priv/main_main.c
index fe3cf9e573c5d75df187eb4b8ee4e6a2b90216bb..0520fd7470e0e73ac0eef4f0c44f6aa7dd219e9a 100644 (file)
--- a/VEX/priv/main_main.c
+++ b/VEX/priv/main_main.c
@@ -1535,9 +1535,6 @@ const HChar* LibVEX_EmNote_string ( VexEmNote ew )
                "  feature requires the floating point extension facility\n"
                "  which is not available on this host. Continuing using\n"
                "  the rounding mode from FPC. Results may differ!";
-     case EmWarn_S390X_invalid_rounding:
-        return "The specified rounding mode is invalid.\n"
-               "  Continuing using 'round to nearest'. Results may differ!";
      case EmFail_S390X_stfle:
         return "Instruction stfle is not supported on this host";
      case EmFail_S390X_stckf:

diff --git a/VEX/pub/libvex_emnote.h b/VEX/pub/libvex_emnote.h
index 27b95880cb833f7e649f92aa1a10b5caeeab5d69..be17a8922f26dfa596d0ab7aacc84cb47975bfbc 100644 (file)
--- a/VEX/pub/libvex_emnote.h
+++ b/VEX/pub/libvex_emnote.h
@@ -89,9 +89,6 @@ typedef
          facility is not available on this host */
       EmWarn_S390X_fpext_rounding,
 
-      /* insn (e.g. srnmb) specifies an invalid rounding mode */
-      EmWarn_S390X_invalid_rounding,
-
       /* stfle insn is not supported on this host */
       EmFail_S390X_stfle,
 

diff --git a/none/tests/s390x/srnmb.c b/none/tests/s390x/srnmb.c
index 548b644ca39978d4cc1521616f100e76e7d14ee0..72fc799fb78b4e49b3afb783d354a5f02c6caaa6 100644 (file)
--- a/none/tests/s390x/srnmb.c
+++ b/none/tests/s390x/srnmb.c
@@ -27,6 +27,7 @@
 
 int main(void)
 {
+   setlinebuf(stdout);
    printf("initial rounding mode = %u\n", get_rounding_mode());
 
    /* Set basic rounding modes in various ways */
@@ -57,7 +58,7 @@ int main(void)
    srnmb(0,001);
    printf("rounding mode = %u\n", get_rounding_mode());
 
-   srnmb0(004);    // -> emul warning invalid rounding mode
+   srnmb0(004);    // -> specification exception
    printf("rounding mode = %u\n", get_rounding_mode());
 
    return 0;

diff --git a/none/tests/s390x/srnmb.stderr.exp b/none/tests/s390x/srnmb.stderr.exp
index b9db22774fd3c783a13a1f1f2badced38b89ea4e..bfdaf8b0ab4499ff52af1edcfb3bf735292bc331 100644 (file)
--- a/none/tests/s390x/srnmb.stderr.exp
+++ b/none/tests/s390x/srnmb.stderr.exp
@@ -1,6 +1,19 @@
 
-Emulation warning: unsupported action:
-  The specified rounding mode is invalid.
-  Continuing using 'round to nearest'. Results may differ!
-   at 0x........: main (srnmb.c:61)
+vex s390->IR: specification exception: B2B8 0004
+valgrind: Unrecognised instruction at address 0x.........
+   at 0x........: main (srnmb.c:59)
+Your program just tried to execute an instruction that Valgrind
+did not recognise.  There are two possible reasons for this.
+1. Your program has a bug and erroneously jumped to a non-code
+   location.  If you are running Memcheck and you just saw a
+   warning about a bad jump, it's probably your program's fault.
+2. The instruction is legitimate but Valgrind doesn't handle it,
+   i.e. it's Valgrind's fault.  If you think this is the case or
+   you are not sure, please let us know and we'll try to fix it.
+Either way, Valgrind will now raise a SIGILL signal which will
+probably kill your program.
+
+Process terminating with default action of signal 4 (SIGILL)
+ Illegal opcode at address 0x........
+   at 0x........: main (srnmb.c:59)
 

diff --git a/none/tests/s390x/srnmb.stdout.exp b/none/tests/s390x/srnmb.stdout.exp
index c2be0f77a2a6f0cfd8eadef26c5228d09bb4aee0..c9127aaf1c2f306d7eb155f3100234e77a7693af 100644 (file)
--- a/none/tests/s390x/srnmb.stdout.exp
+++ b/none/tests/s390x/srnmb.stdout.exp
@@ -4,4 +4,3 @@ rounding mode = 2
 rounding mode = 1
 rounding mode = 0
 rounding mode = 1
-rounding mode = 0