diff --git a/compiler/src/dmd/backend/cdef.d b/compiler/src/dmd/backend/cdef.d
index ba7a9c50fcbf..e802592d40ed 100644
--- a/compiler/src/dmd/backend/cdef.d
+++ b/compiler/src/dmd/backend/cdef.d
@@ -596,7 +596,7 @@ struct Configv
 }
 
 alias reg_t = ubyte;            // register number
-alias regm_t = uint;            // Register mask type
+alias regm_t = ulong;           // Register mask type
 struct immed_t
 {
     targ_size_t[REGMAX] value;  // immediate values in registers
diff --git a/compiler/src/dmd/backend/code.d b/compiler/src/dmd/backend/code.d
index bda5df9366a1..42ab31833ba7 100644
--- a/compiler/src/dmd/backend/code.d
+++ b/compiler/src/dmd/backend/code.d
@@ -356,8 +356,8 @@ enum BackendPass
 
 public import dmd.backend.x86.cgcod : findreg;
 
-reg_t findregmsw(uint regm) { return findreg(regm & mMSW); }
-reg_t findreglsw(uint regm) { return findreg(regm & (mLSW | mBP)); }
+reg_t findregmsw(regm_t regm) { return findreg(regm & mMSW); }
+reg_t findreglsw(regm_t regm) { return findreg(regm & (mLSW | mBP)); }
 
 public import dmd.backend.x86.cod1;
 public import dmd.backend.x86.cod2;
diff --git a/compiler/src/dmd/backend/global.d b/compiler/src/dmd/backend/global.d
index ce10b87348ce..24e064ce45ac 100644
--- a/compiler/src/dmd/backend/global.d
+++ b/compiler/src/dmd/backend/global.d
@@ -98,7 +98,7 @@ int REGSIZE() @trusted { return _tysize[TYnptr]; }
 public import dmd.backend.var : debuga, debugb, debugc, debugd, debuge, debugf,
     debugr, debugs, debugt, debugu, debugw, debugx, debugy;
 
-extern (D) uint mask(uint m) { return 1 << m; }
+extern (D) regm_t mask(uint m) { return cast(regm_t)1 << m; }
 
 public import dmd.backend.var : OPTIMIZER, PARSER, globsym, controlc_saw, pointertype, sytab;
 public import dmd.backend.cg : fregsaved, localgot, tls_get_addr_sym;
diff --git a/compiler/src/dmd/backend/x86/cgcod.d b/compiler/src/dmd/backend/x86/cgcod.d
index 996a50ce821a..a502737a7554 100644
--- a/compiler/src/dmd/backend/x86/cgcod.d
+++ b/compiler/src/dmd/backend/x86/cgcod.d
@@ -2964,7 +2964,7 @@ const(char)* regm_str(regm_t rm)
     {
         const pstrlen = strlen(p);
         char *s = p + pstrlen;
-        snprintf(s, SMAX - pstrlen, "x%02x",rm);
+        snprintf(s, SMAX - pstrlen, "x%02llx", cast(ulong)rm);
     }
     assert(strlen(p) <= SMAX);
     return strdup(p);
diff --git a/compiler/src/dmd/backend/x86/cod1.d b/compiler/src/dmd/backend/x86/cod1.d
index 5656393c9875..0f342836756e 100644
--- a/compiler/src/dmd/backend/x86/cod1.d
+++ b/compiler/src/dmd/backend/x86/cod1.d
@@ -1715,7 +1715,7 @@ void fltregs(ref CodeBuilder cdb, code* pcs, tym_t tym)
  */
 
 @trusted
-void tstresult(ref CodeBuilder cdb, regm_t regm, tym_t tym, uint saveflag)
+void tstresult(ref CodeBuilder cdb, regm_t regm, tym_t tym, bool saveflag)
 {
     reg_t scrreg;                      // scratch register
     regm_t scrregm;
@@ -2036,7 +2036,7 @@ void fixresult(ref CodeBuilder cdb, elem *e, regm_t retregs, ref regm_t outretre
             fixresult87(cdb, e, retregs, outretregs);
         }
         else
-            tstresult(cdb, retregs, tym, forregs);
+            tstresult(cdb, retregs, tym, forregs != 0);
     }
 }
 
diff --git a/compiler/src/dmd/backend/x86/cod2.d b/compiler/src/dmd/backend/x86/cod2.d
index 03fcf3c2240f..ea6084452bc8 100644
--- a/compiler/src/dmd/backend/x86/cod2.d
+++ b/compiler/src/dmd/backend/x86/cod2.d
@@ -1174,8 +1174,8 @@ void cdmul(ref CGstate cg, ref CodeBuilder cdb,elem *e,regm_t *pretregs)
                 {
                     regm_t rretregs = cgstate.allregs & ~retregs;           // second arg
                     scodelem(cgstate,cdb,e2,&rretregs,retregs,true); // get rvalue
-                    regm_t rlo = findreglsw(rretregs);
-                    regm_t rhi = findregmsw(rretregs);
+                    reg_t rlo = findreglsw(rretregs);
+                    reg_t rhi = findregmsw(rretregs);
                     /*  IMUL    rhi,EAX
                         IMUL    EDX,rlo
                         ADD     rhi,EDX
diff --git a/compiler/src/dmd/backend/x86/cod4.d b/compiler/src/dmd/backend/x86/cod4.d
index 57e53577ee5e..7395e8d5ddb5 100644
--- a/compiler/src/dmd/backend/x86/cod4.d
+++ b/compiler/src/dmd/backend/x86/cod4.d
@@ -1639,8 +1639,8 @@ void cdmulass(ref CGstate cg, ref CodeBuilder cdb,elem *e,regm_t *pretregs)
             getlvalue_lsw(cs);
             if (config.target_cpu >= TARGET_PentiumPro)
             {
-                regm_t rlo = findreglsw(rretregs);
-                regm_t rhi = findregmsw(rretregs);
+                reg_t rlo = findreglsw(rretregs);
+                reg_t rhi = findregmsw(rretregs);
                 /*  IMUL    rhi,EAX
                     IMUL    EDX,rlo
                     ADD     rhi,EDX