From 7852cc600d0bbb89c068b595caef59c889f410c6 Mon Sep 17 00:00:00 2001
From: Richard Henderson <rth@twiddle.net>
Date: Thu, 1 Mar 2018 11:04:30 -0500
Subject: [PATCH] tcg/s390: Fix setcond expansion

We can't use LOAD AND TEST for unsigned data and then expect to
extract the result with ADD LOGICAL WITH CARRY. Fall through to
using COMPARE LOGICAL IMMEDIATE instead.

Backports commit 65839b56b9a740e6b898b5d81afc160502bd2935 from qemu
---
 qemu/tcg/s390/tcg-target.inc.c | 56 ++++++++++++++++++++--------------
 1 file changed, 33 insertions(+), 23 deletions(-)

diff --git a/qemu/tcg/s390/tcg-target.inc.c b/qemu/tcg/s390/tcg-target.inc.c
index bd9034c6..8a6a404b 100644
--- a/qemu/tcg/s390/tcg-target.inc.c
+++ b/qemu/tcg/s390/tcg-target.inc.c
@@ -1098,33 +1098,43 @@ static void tgen64_xori(TCGContext *s, TCGReg dest, tcg_target_ulong val)
 }
 
 static int tgen_cmp(TCGContext *s, TCGType type, TCGCond c, TCGReg r1,
-                    TCGArg c2, int c2const)
+                    TCGArg c2, bool c2const, bool need_carry)
 {
     bool is_unsigned = is_unsigned_cond(c);
     if (c2const) {
         if (c2 == 0) {
-            if (type == TCG_TYPE_I32) {
-                tcg_out_insn(s, RR, LTR, r1, r1);
-            } else {
-                tcg_out_insn(s, RRE, LTGR, r1, r1);
+            if (!(is_unsigned && need_carry)) {
+                if (type == TCG_TYPE_I32) {
+                    tcg_out_insn(s, RR, LTR, r1, r1);
+                } else {
+                    tcg_out_insn(s, RRE, LTGR, r1, r1);
+                }
+                return tcg_cond_to_ltr_cond[c];
             }
-            return tcg_cond_to_ltr_cond[c];
-        } else {
-            if (is_unsigned) {
-                if (type == TCG_TYPE_I32) {
-                    tcg_out_insn(s, RIL, CLFI, r1, c2);
-                } else {
-                    tcg_out_insn(s, RIL, CLGFI, r1, c2);
-                }
+            /* If we only got here because of load-and-test,
+               and we couldn't use that, then we need to load
+               the constant into a register.  */
+            if (!(facilities & FACILITY_EXT_IMM)) {
+                c2 = TCG_TMP0;
+                tcg_out_movi(s, type, c2, 0);
+                goto do_reg;
+            }
+        }
+        if (is_unsigned) {
+            if (type == TCG_TYPE_I32) {
+                tcg_out_insn(s, RIL, CLFI, r1, c2);
             } else {
-                if (type == TCG_TYPE_I32) {
-                    tcg_out_insn(s, RIL, CFI, r1, c2);
-                } else {
-                    tcg_out_insn(s, RIL, CGFI, r1, c2);
-                }
+                tcg_out_insn(s, RIL, CLGFI, r1, c2);
+            }
+        } else {
+            if (type == TCG_TYPE_I32) {
+                tcg_out_insn(s, RIL, CFI, r1, c2);
+            } else {
+                tcg_out_insn(s, RIL, CGFI, r1, c2);
             }
         }
     } else {
+    do_reg:
         if (is_unsigned) {
             if (type == TCG_TYPE_I32) {
                 tcg_out_insn(s, RR, CLR, r1, c2);
@@ -1153,7 +1163,7 @@ static void tgen_setcond(TCGContext *s, TCGType type, TCGCond cond,
     do_greater:
         /* The result of a compare has CC=2 for GT and CC=3 unused.
            ADD LOGICAL WITH CARRY considers (CC & 2) the carry bit.  */
-        tgen_cmp(s, type, cond, c1, c2, c2const);
+        tgen_cmp(s, type, cond, c1, c2, c2const, true);
         tcg_out_movi(s, type, dest, 0);
         tcg_out_insn(s, RRE, ALCGR, dest, dest);
         return;
@@ -1224,7 +1234,7 @@ static void tgen_setcond(TCGContext *s, TCGType type, TCGCond cond,
         break;
     }
 
-    cc = tgen_cmp(s, type, cond, c1, c2, c2const);
+    cc = tgen_cmp(s, type, cond, c1, c2, c2const, false);
     if (facilities & FACILITY_LOAD_ON_COND) {
         /* Emit: d = 0, t = 1, d = (cc ? t : d).  */
         tcg_out_movi(s, TCG_TYPE_I64, dest, 0);
@@ -1243,11 +1253,11 @@ static void tgen_movcond(TCGContext *s, TCGType type, TCGCond c, TCGReg dest,
 {
     int cc;
     if (facilities & FACILITY_LOAD_ON_COND) {
-        cc = tgen_cmp(s, type, c, c1, c2, c2const);
+        cc = tgen_cmp(s, type, c, c1, c2, c2const, false);
         tcg_out_insn(s, RRF, LOCGR, dest, r3, cc);
     } else {
         c = tcg_invert_cond(c);
-        cc = tgen_cmp(s, type, c, c1, c2, c2const);
+        cc = tgen_cmp(s, type, c, c1, c2, c2const, false);
 
         /* Emit: if (cc) goto over; dest = r3; over:  */
         tcg_out_insn(s, RI, BRC, cc, (4 + 4) >> 1);
@@ -1379,7 +1389,7 @@ static void tgen_brcond(TCGContext *s, TCGType type, TCGCond c,
         }
     }
 
-    cc = tgen_cmp(s, type, c, r1, c2, c2const);
+    cc = tgen_cmp(s, type, c, r1, c2, c2const, false);
     tgen_branch(s, cc, l);
 }