Add support for using MVN to materialize negative constants.

rdar://10412592

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144348 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/ARMFastISel.cpp

@@ -552,16 +552,30 @@ unsigned ARMFastISel::ARMMaterializeInt(const Constant *C, EVT VT) {
   // do so now.
   const ConstantInt *CI = cast<ConstantInt>(C);
   if (Subtarget->hasV6T2Ops() && isUInt<16>(CI->getZExtValue())) {
-    EVT SrcVT = MVT::i32;
     unsigned Opc = isThumb2 ? ARM::t2MOVi16 : ARM::MOVi16;
-    unsigned ImmReg = createResultReg(TLI.getRegClassFor(SrcVT));
+    unsigned ImmReg = createResultReg(TLI.getRegClassFor(MVT::i32));
     AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
                             TII.get(Opc), ImmReg)
                     .addImm(CI->getZExtValue()));
     return ImmReg;
   }
 
-  // For now 32-bit only.
+  // Use MVN to emit negative constants.
+  if (VT == MVT::i32 && Subtarget->hasV6T2Ops() && CI->isNegative()) {
+    unsigned Imm = (unsigned)~(CI->getSExtValue());
+    bool EncodeImm = isThumb2 ? (ARM_AM::getT2SOImmVal(Imm) != -1) :
+      (ARM_AM::getSOImmVal(Imm) != -1);
+    if (EncodeImm) {
+      unsigned Opc = isThumb2 ? ARM::t2MVNi : ARM::MVNi;
+      unsigned ImmReg = createResultReg(TLI.getRegClassFor(MVT::i32));
+      AddOptionalDefs(BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+                              TII.get(Opc), ImmReg)
+                      .addImm(Imm));
+      return ImmReg;
+    }
+  }
+
+  // Load from constant pool.  For now 32-bit only.
   if (VT != MVT::i32)
     return false;
 

test/CodeGen/ARM/fast-isel-ldrh-strh-arm.ll

@@ -11,7 +11,7 @@ entry:
 ; ARM: t1
   %add.ptr = getelementptr inbounds i16* %a, i64 -8
   %0 = load i16* %add.ptr, align 2
-; ARM: ldr r{{[1-9]}}, LCPI0_0
+; ARM: mvn r{{[1-9]}}, #15
 ; ARM: add r0, r0, r{{[1-9]}}
 ; ARM: ldrh r0, [r0]
   ret i16 %0
@@ -23,7 +23,7 @@ entry:
 ; ARM: t2
   %add.ptr = getelementptr inbounds i16* %a, i64 -16
   %0 = load i16* %add.ptr, align 2
-; ARM: ldr r{{[1-9]}}, LCPI1_0
+; ARM: mvn r{{[1-9]}}, #31
 ; ARM: add r0, r0, r{{[1-9]}}
 ; ARM: ldrh r0, [r0]
   ret i16 %0
@@ -35,7 +35,7 @@ entry:
 ; ARM: t3
   %add.ptr = getelementptr inbounds i16* %a, i64 -127
   %0 = load i16* %add.ptr, align 2
-; ARM: ldr r{{[1-9]}}, LCPI2_0
+; ARM: mvn r{{[1-9]}}, #253
 ; ARM: add r0, r0, r{{[1-9]}}
 ; ARM: ldrh r0, [r0]
   ret i16 %0
@@ -48,7 +48,7 @@ entry:
 ; ARM: t4
   %add.ptr = getelementptr inbounds i16* %a, i64 -128
   %0 = load i16* %add.ptr, align 2
-; ARM: ldr r{{[1-9]}}, LCPI3_0
+; ARM: mvn r{{[1-9]}}, #255
 ; ARM: add r0, r0, r{{[1-9]}}
 ; ARM: ldrh r0, [r0]
   ret i16 %0
@@ -97,7 +97,7 @@ entry:
 ; ARM: t9
   %add.ptr = getelementptr inbounds i16* %a, i64 -8
   store i16 0, i16* %add.ptr, align 2
-; ARM: ldr r{{[1-9]}}, LCPI8_0
+; ARM: mvn r{{[1-9]}}, #15
 ; ARM: add r0, r0, r{{[1-9]}}
 ; ARM: strh r{{[1-9]}}, [r0]
   ret void
@@ -110,7 +110,7 @@ entry:
 ; ARM: t10
   %add.ptr = getelementptr inbounds i16* %a, i64 -128
   store i16 0, i16* %add.ptr, align 2
-; ARM: ldr r{{[1-9]}}, LCPI9_0
+; ARM: mvn r{{[1-9]}}, #255
 ; ARM: add r0, r0, r{{[1-9]}}
 ; ARM: strh r{{[1-9]}}, [r0]
   ret void

test/CodeGen/ARM/fast-isel-mvn.ll

@@ -0,0 +1,107 @@
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=armv7-apple-darwin | FileCheck %s --check-prefix=ARM
+; RUN: llc < %s -O0 -fast-isel-abort -relocation-model=dynamic-no-pic -mtriple=thumbv7-apple-darwin | FileCheck %s --check-prefix=THUMB
+; rdar://10412592
+
+; Note: The Thumb code is being generated by the target-independent selector.
+
+define void @t1() nounwind {
+entry:
+; ARM: t1
+; THUMB: t1
+; ARM: mvn r0, #0
+; THUMB: movw r0, #65535
+; THUMB: movt r0, #65535
+  call void @foo(i32 -1)
+  ret void
+}
+
+declare void @foo(i32)
+
+define void @t2() nounwind {
+entry:
+; ARM: t2
+; THUMB: t2
+; ARM: mvn r0, #233
+; THUMB: movw r0, #65302
+; THUMB: movt r0, #65535
+  call void @foo(i32 -234)
+  ret void
+}
+
+define void @t3() nounwind {
+entry:
+; ARM: t3
+; THUMB: t3
+; ARM: mvn	r0, #256
+; THUMB: movw r0, #65279
+; THUMB: movt r0, #65535
+  call void @foo(i32 -257)
+  ret void
+}
+
+; Load from constant pool
+define void @t4() nounwind {
+entry:
+; ARM: t4
+; THUMB: t4
+; ARM: ldr	r0
+; THUMB: movw r0, #65278
+; THUMB: movt r0, #65535
+  call void @foo(i32 -258)
+  ret void
+}
+
+define void @t5() nounwind {
+entry:
+; ARM: t5
+; THUMB: t5
+; ARM: mvn r0, #65280
+; THUMB: movs r0, #255
+; THUMB: movt r0, #65535
+  call void @foo(i32 -65281)
+  ret void
+}
+
+define void @t6() nounwind {
+entry:
+; ARM: t6
+; THUMB: t6
+; ARM: mvn r0, #978944
+; THUMB: movw r0, #4095
+; THUMB: movt r0, #65521
+  call void @foo(i32 -978945)
+  ret void
+}
+
+define void @t7() nounwind {
+entry:
+; ARM: t7
+; THUMB: t7
+; ARM: mvn r0, #267386880
+; THUMB: movw r0, #65535
+; THUMB: movt r0, #61455
+  call void @foo(i32 -267386881)
+  ret void
+}
+
+define void @t8() nounwind {
+entry:
+; ARM: t8
+; THUMB: t8
+; ARM: mvn r0, #65280
+; THUMB: movs r0, #255
+; THUMB: movt r0, #65535
+  call void @foo(i32 -65281)
+  ret void
+}
+
+define void @t9() nounwind {
+entry:
+; ARM: t9
+; THUMB: t9
+; ARM: mvn r0, #2130706432
+; THUMB: movw r0, #65535
+; THUMB: movt r0, #33023
+  call void @foo(i32 -2130706433)
+  ret void
+}