Add an alternative rev16 pattern. We should figure out a better way t…

…o handle these complex rev patterns. rdar://9609108

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133289 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/ARMInstrInfo.td

@@ -3017,6 +3017,12 @@ def REV16 : AMiscA1I<0b01101011, 0b1011, (outs GPR:$Rd), (ins GPR:$Rm),
                                (and (shl GPR:$Rm, (i32 8)), 0xFF000000)))))]>,
                Requires<[IsARM, HasV6]>;
 
+def : ARMV6Pat<(or (or (or (and (srl GPR:$Rm, (i32 8)), 0xFF0000),
+                           (and (shl GPR:$Rm, (i32 8)), 0xFF000000)),
+                       (and (srl GPR:$Rm, (i32 8)), 0xFF)),
+                   (and (shl GPR:$Rm, (i32 8)), 0xFF00)),
+               (REV16 GPR:$Rm)>;
+
 def REVSH : AMiscA1I<0b01101111, 0b1011, (outs GPR:$Rd), (ins GPR:$Rm),
                IIC_iUNAr, "revsh", "\t$Rd, $Rm",
                [(set GPR:$Rd,

lib/Target/ARM/ARMInstrThumb2.td

@@ -2593,6 +2593,12 @@ def t2REV16 : T2I_misc<0b01, 0b01, (outs rGPR:$Rd), (ins rGPR:$Rm), IIC_iUNAr,
                             (or (and (srl rGPR:$Rm, (i32 8)), 0xFF0000),
                                (and (shl rGPR:$Rm, (i32 8)), 0xFF000000)))))]>;
 
+def : T2Pat<(or (or (or (and (srl rGPR:$Rm, (i32 8)), 0xFF0000),
+                        (and (shl rGPR:$Rm, (i32 8)), 0xFF000000)),
+                    (and (srl rGPR:$Rm, (i32 8)), 0xFF)),
+                (and (shl rGPR:$Rm, (i32 8)), 0xFF00)),
+            (t2REV16 rGPR:$Rm)>;
+
 def t2REVSH : T2I_misc<0b01, 0b11, (outs rGPR:$Rd), (ins rGPR:$Rm), IIC_iUNAr,
                        "revsh", ".w\t$Rd, $Rm",
                  [(set rGPR:$Rd,

test/CodeGen/ARM/rev.ll

@@ -67,3 +67,20 @@ entry:
   %or = or i32 %shr, %and
   ret i32 %or
 }
+
+; rdar://9609108
+define i32 @test6(i32 %x) nounwind readnone {
+entry:
+; CHECK: test6
+; CHECK: rev16 r0, r0
+  %and = shl i32 %x, 8
+  %shl = and i32 %and, 65280
+  %and2 = lshr i32 %x, 8
+  %shr11 = and i32 %and2, 255
+  %shr5 = and i32 %and2, 16711680
+  %shl9 = and i32 %and, -16777216
+  %or = or i32 %shr5, %shl9
+  %or6 = or i32 %or, %shr11
+  %or10 = or i32 %or6, %shl
+  ret i32 %or10
+}