fix Issue 24257 - ImportC: ICE on accessing last _Bool bitfield (#15861)

dlang · Nov 25, 2023 · e1197fc · e1197fc
1 parent 27b891c
commit e1197fc
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Showing 2 changed files with 62 additions and 6 deletions.
diff --git a/compiler/src/dmd/e2ir.d b/compiler/src/dmd/e2ir.d
@@ -3096,16 +3096,36 @@ elem* toElem(Expression e, ref IRState irs)
             e = addressElem(e, tb1);
             typ = tybasic(e.Ety);
         }
-        auto offset = el_long(TYsize_t, v.offset);
-        offset = objc.getOffset(v, tb1, offset);
-        e = el_bin(OPadd, typ, e, offset);
+
+        const tym = totym(dve.type);
+        auto voffset = v.offset;
+        uint bitfieldarg = 0;
+        auto bf = v.isBitFieldDeclaration();
+        if (bf)
+        {
+            // adjust bit offset for bitfield so the type tym encloses the bitfield
+            const szbits = tysize(tym) * 8;
+            auto bitOffset = bf.bitOffset;
+            if (bitOffset + bf.fieldWidth > szbits)
+            {
+                const advance = bf.bitOffset / szbits;
+                voffset += advance;
+                bitOffset -= advance * 8;
+                assert(bitOffset + bf.fieldWidth <= szbits);
+            }
+            //printf("voffset %u bitOffset %u fieldWidth %u bits %u\n", cast(uint)voffset, bitOffset, bf.fieldWidth, szbits);
+            bitfieldarg = bf.fieldWidth * 256 + bitOffset;
+        }
+
+        auto eoffset = el_long(TYsize_t, voffset);
+        e = el_bin(OPadd, typ, e, objc.getOffset(v, tb1, eoffset));
         if (v.storage_class & (STC.out_ | STC.ref_))
             e = el_una(OPind, TYnptr, e);
-        e = el_una(OPind, totym(dve.type), e);
-        if (auto bf = v.isBitFieldDeclaration())
+        e = el_una(OPind, tym, e);
+        if (bf)
         {
             // Insert special bitfield operator
-            auto mos = el_long(TYuint, bf.fieldWidth * 256 + bf.bitOffset);
+            auto mos = el_long(TYuint, bitfieldarg);
             e = el_bin(OPbit, e.Ety, e, mos);
         }
         if (tybasic(e.Ety) == TYstruct)
@@ -6561,6 +6581,8 @@ elem *toElemStructLit(StructLiteralExp sle, ref IRState irs, EXP op, Symbol *sym
                     {
                         // Insert special bitfield operator
                         auto mos = el_long(TYuint, bf.fieldWidth * 256 + bf.bitOffset);
+                        //printf("2bitOffset %u fieldWidth %u bits %u\n", bf.bitOffset, bf.fieldWidth, tysize(e1.Ety) * 8);
+                        assert(bf.bitOffset + bf.fieldWidth <= tysize(e1.Ety) * 8);
                         e1 = el_bin(OPbit, e1.Ety, e1, mos);
                     }
                 }

diff --git a/compiler/test/runnable/dbitfields.d b/compiler/test/runnable/dbitfields.d
@@ -173,6 +173,39 @@ static assert(test7u() ==  1);
 static assert(test7s() == -1);
 static assert(test7s2() == -2);
 
+/******************************************/
+// https://issues.dlang.org/show_bug.cgi?id=24257
+
+struct S24257
+{
+    uint : 15;
+    bool done : 1;
+}
+
+bool advance()
+{
+    S24257 n;
+    n.done = false;
+    n.done = true;
+    return n.done;
+}
+
+bool retard()
+{
+    S24257 n;
+    n.done = true;
+    n.done = false;
+    return n.done;
+}
+
+static assert(advance() == true);
+
+void test24257()
+{
+    assert(advance() == true);
+    assert(retard() == false);
+}
+
 /******************************************/
 
 int main()
@@ -184,6 +217,7 @@ int main()
     test5();
     test6();
     test7();
+    test24257();
 
     return 0;
 }