fix Issue 15538 - [REG 2.064] wrong code with switch

dlang · Oct 7, 2017 · ef56ed9 · ef56ed9
1 parent 2f98e66
commit ef56ed9
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Showing 2 changed files with 33 additions and 2 deletions.
diff --git a/src/ddmd/backend/cod3.c b/src/ddmd/backend/cod3.c
@@ -1303,6 +1303,7 @@ void doswitch(CodeBuilder& cdb, block *b)
     bool csseg = false;
 #endif
 
+    //printf("doswitch(%d)\n", b->BC);
     elem *e = b->Belem;
     elem_debug(e);
     docommas(cdb,&e);
@@ -1463,15 +1464,16 @@ void doswitch(CodeBuilder& cdb, block *b)
         if (vmax - vmin != REGMASK)     // if there is a maximum
         {                               // CMP reg,vmax-vmin
             cdb.genc2(0x81,modregrm(3,7,reg),vmax-vmin);
-            if (I64)
+            if (I64 && sz == 8)
                 code_orrex(cdb.last(), REX_W);
             genjmp(cdb,JA,FLblock,b->nthSucc(0));  // JA default
         }
         if (I64)
         {
             if (!vmin)
             {   // Need to clear out high 32 bits of reg
-                genmovreg(cdb,reg,reg);                       // MOV reg,reg
+                // Use 8B instead of 89, as 89 will be optimized away as a NOP
+                genregs(cdb,0x8B,reg,reg);                 // MOV reg,reg
             }
             if (config.flags3 & CFG3pic || config.exe == EX_WIN64)
             {

diff --git a/test/runnable/testswitch.d b/test/runnable/testswitch.d
@@ -703,6 +703,34 @@ void test15396()
 
 /*****************************************/
 
+// https://issues.dlang.org/show_bug.cgi?id=15538
+
+struct S15538
+{
+    int a = 0;
+    int b = 1;
+}
+
+int f15538(S15538 s)
+{
+    switch (s.a)
+    {
+        case 0: return 10;
+        case 1: return 20;
+        case 2: return 30;
+        case 3: return 40;
+        default: return 99;
+    }
+}
+
+void test15538()
+{
+    S15538 s;
+    assert(f15538(s) == 10); /* fails */
+}
+
+/*****************************************/
+
 int main()
 {
     test1();
@@ -732,6 +760,7 @@ int main()
     test14352();
     test14587();
     test15396();
+    test15538();
 
     printf("Success\n");
     return 0;