Initial bits of ARMv4-only support.

Patch by John Tytgat!

llvm-svn: 97886

lib/Target/ARM/ARMBaseInstrInfo.h

@@ -332,7 +332,7 @@ bool isJumpTableBranchOpcode(int Opc) {
 
 static inline
 bool isIndirectBranchOpcode(int Opc) {
-  return Opc == ARM::BRIND || Opc == ARM::tBRIND;
+  return Opc == ARM::BRIND || Opc == ARM::MOVPCRX || Opc == ARM::tBRIND;
 }
 
 /// getInstrPredicate - If instruction is predicated, returns its predicate

lib/Target/ARM/ARMCodeEmitter.cpp

@@ -1138,7 +1138,7 @@ void ARMCodeEmitter::emitMiscBranchInstruction(const MachineInstr &MI) {
   // Set the conditional execution predicate
   Binary |= II->getPredicate(&MI) << ARMII::CondShift;
 
-  if (TID.Opcode == ARM::BX_RET)
+  if (TID.Opcode == ARM::BX_RET || TID.Opcode == ARM::MOVPCLR)
     // The return register is LR.
     Binary |= ARMRegisterInfo::getRegisterNumbering(ARM::LR);
   else

lib/Target/ARM/ARMInstrInfo.td

@@ -113,6 +113,8 @@ def ARMrbit          : SDNode<"ARMISD::RBIT", SDTIntUnaryOp>;
 //===----------------------------------------------------------------------===//
 // ARM Instruction Predicate Definitions.
 //
+def HasV4T    : Predicate<"Subtarget->hasV4TOps()">;
+def NoV4T     : Predicate<"!Subtarget->hasV4TOps()">;
 def HasV5T    : Predicate<"Subtarget->hasV5TOps()">;
 def HasV5TE   : Predicate<"Subtarget->hasV5TEOps()">;
 def HasV6     : Predicate<"Subtarget->hasV6Ops()">;
@@ -851,24 +853,50 @@ def LEApcrelJT : AXI1<0x0, (outs GPR:$dst),
 //  Control Flow Instructions.
 //
 
-let isReturn = 1, isTerminator = 1, isBarrier = 1 in
+let isReturn = 1, isTerminator = 1, isBarrier = 1 in {
+  // ARMV4T and above
   def BX_RET : AI<(outs), (ins), BrMiscFrm, IIC_Br,
-                  "bx", "\tlr", [(ARMretflag)]> {
+                  "bx", "\tlr", [(ARMretflag)]>,
-  let Inst{3-0}   = 0b1110;
+               Requires<[IsARM, HasV4T]> {
-  let Inst{7-4}   = 0b0001;
+    let Inst{3-0}   = 0b1110;
-  let Inst{19-8}  = 0b111111111111;
+    let Inst{7-4}   = 0b0001;
-  let Inst{27-20} = 0b00010010;
+    let Inst{19-8}  = 0b111111111111;
+    let Inst{27-20} = 0b00010010;
+  }
+
+  // ARMV4 only
+  def MOVPCLR : AI<(outs), (ins), BrMiscFrm, IIC_Br, 
+                  "mov", "\tpc, lr", [(ARMretflag)]>,
+               Requires<[IsARM, NoV4T]> {
+    let Inst{11-0}  = 0b000000001110;
+    let Inst{15-12} = 0b1111;
+    let Inst{19-16} = 0b0000;
+    let Inst{27-20} = 0b00011010;
+  }
 }
 
 // Indirect branches
 let isBranch = 1, isTerminator = 1, isBarrier = 1, isIndirectBranch = 1 in {
+  // ARMV4T and above
   def BRIND : AXI<(outs), (ins GPR:$dst), BrMiscFrm, IIC_Br, "bx\t$dst",
-                  [(brind GPR:$dst)]> {
+                  [(brind GPR:$dst)]>,
+              Requires<[IsARM, HasV4T]> {
     let Inst{7-4}   = 0b0001;
     let Inst{19-8}  = 0b111111111111;
     let Inst{27-20} = 0b00010010;
     let Inst{31-28} = 0b1110;
   }
+
+  // ARMV4 only
+  def MOVPCRX : AXI<(outs), (ins GPR:$dst), BrMiscFrm, IIC_Br, "mov\tpc, $dst",
+                  [(brind GPR:$dst)]>,
+              Requires<[IsARM, NoV4T]> {
+    let Inst{11-4}  = 0b00000000;
+    let Inst{15-12} = 0b1111;
+    let Inst{19-16} = 0b0000;
+    let Inst{27-20} = 0b00011010;
+    let Inst{31-28} = 0b1110;
+  }
 }
 
 // FIXME: remove when we have a way to marking a MI with these properties.
@@ -913,11 +941,22 @@ let isCall = 1,
   def BX : ABXIx2<(outs), (ins tGPR:$func, variable_ops),
                   IIC_Br, "mov\tlr, pc\n\tbx\t$func",
                   [(ARMcall_nolink tGPR:$func)]>,
-           Requires<[IsARM, IsNotDarwin]> {
+           Requires<[IsARM, HasV4T, IsNotDarwin]> {
     let Inst{7-4}   = 0b0001;
     let Inst{19-8}  = 0b111111111111;
     let Inst{27-20} = 0b00010010;
   }
+
+  // ARMv4
+  def BMOVPCRX : ABXIx2<(outs), (ins tGPR:$func, variable_ops),
+                 IIC_Br, "mov\tlr, pc\n\tmov\tpc, $func",
+                 [(ARMcall_nolink tGPR:$func)]>,
+           Requires<[IsARM, NoV4T, IsNotDarwin]> {
+    let Inst{11-4}  = 0b00000000;
+    let Inst{15-12} = 0b1111;
+    let Inst{19-16} = 0b0000;
+    let Inst{27-20} = 0b00011010;
+  }
 }
 
 // On Darwin R9 is call-clobbered.
@@ -950,11 +989,23 @@ let isCall = 1,
   // Note: Restrict $func to the tGPR regclass to prevent it being in LR.
   def BXr9 : ABXIx2<(outs), (ins tGPR:$func, variable_ops),
                   IIC_Br, "mov\tlr, pc\n\tbx\t$func",
-                  [(ARMcall_nolink tGPR:$func)]>, Requires<[IsARM, IsDarwin]> {
+                  [(ARMcall_nolink tGPR:$func)]>,
+             Requires<[IsARM, HasV4T, IsDarwin]> {
     let Inst{7-4}   = 0b0001;
     let Inst{19-8}  = 0b111111111111;
     let Inst{27-20} = 0b00010010;
   }
+
+  // ARMv4
+  def BMOVPCRXr9 : ABXIx2<(outs), (ins tGPR:$func, variable_ops),
+                 IIC_Br, "mov\tlr, pc\n\tmov\tpc, $func",
+                 [(ARMcall_nolink tGPR:$func)]>,
+           Requires<[IsARM, NoV4T, IsDarwin]> {
+    let Inst{11-4}  = 0b00000000;
+    let Inst{15-12} = 0b1111;
+    let Inst{19-16} = 0b0000;
+    let Inst{27-20} = 0b00011010;
+  }
 }
 
 let isBranch = 1, isTerminator = 1 in {

lib/Target/ARM/ARMSubtarget.cpp

@@ -33,7 +33,7 @@ UseMOVT("arm-use-movt",
 
 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
                            bool isT)
-  : ARMArchVersion(V4T)
+  : ARMArchVersion(V4)
   , ARMFPUType(None)
   , UseNEONForSinglePrecisionFP(UseNEONFP)
   , IsThumb(isT)
@@ -54,6 +54,11 @@ ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
   // Parse features string.
   CPUString = ParseSubtargetFeatures(FS, CPUString);
 
+  // When no arch is specified either by CPU or by attributes, make the default
+  // ARMv4T.
+  if (CPUString == "generic" && (FS.empty() || FS == "generic"))
+    ARMArchVersion = V4T;
+
   // Set the boolean corresponding to the current target triple, or the default
   // if one cannot be determined, to true.
   unsigned Len = TT.length();
@@ -68,25 +73,28 @@ ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
   }
   if (Idx) {
     unsigned SubVer = TT[Idx];
-    if (SubVer > '4' && SubVer <= '9') {
+    if (SubVer >= '7' && SubVer <= '9') {
-      if (SubVer >= '7') {
+      ARMArchVersion = V7A;
-        ARMArchVersion = V7A;
+    } else if (SubVer == '6') {
-      } else if (SubVer == '6') {
+      ARMArchVersion = V6;
-        ARMArchVersion = V6;
+      if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
-        if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
+        ARMArchVersion = V6T2;
-          ARMArchVersion = V6T2;
+    } else if (SubVer == '5') {
-      } else if (SubVer == '5') {
+      ARMArchVersion = V5T;
-        ARMArchVersion = V5T;
+      if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e')
-        if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e')
+        ARMArchVersion = V5TE;
-          ARMArchVersion = V5TE;
+    } else if (SubVer == '4') {
-      }
+      if (Len >= Idx+2 && TT[Idx+1] == 't')
-      if (ARMArchVersion >= V6T2)
+        ARMArchVersion = V4T;
-        ThumbMode = Thumb2;
+      else
+        ARMArchVersion = V4;
     }
   }
 
   // Thumb2 implies at least V6T2.
-  if (ARMArchVersion < V6T2 && ThumbMode >= Thumb2)
+  if (ARMArchVersion >= V6T2)
+    ThumbMode = Thumb2;
+  else if (ThumbMode >= Thumb2)
     ARMArchVersion = V6T2;
 
   if (Len >= 10) {

lib/Target/ARM/ARMSubtarget.h

@@ -26,7 +26,7 @@ class GlobalValue;
 class ARMSubtarget : public TargetSubtarget {
 protected:
   enum ARMArchEnum {
-    V4T, V5T, V5TE, V6, V6T2, V7A
+    V4, V4T, V5T, V5TE, V6, V6T2, V7A
   };
 
   enum ARMFPEnum {
@@ -38,7 +38,7 @@ protected:
     Thumb2
   };
 
-  /// ARMArchVersion - ARM architecture version: V4T (base), V5T, V5TE,
+  /// ARMArchVersion - ARM architecture version: V4, V4T (base), V5T, V5TE,
   /// V6, V6T2, V7A.
   ARMArchEnum ARMArchVersion;
 

test/CodeGen/ARM/armv4.ll

@@ -0,0 +1,13 @@
+; RUN: llc < %s -mtriple=arm-unknown-eabi | FileCheck %s -check-prefix=THUMB
+; RUN: llc < %s -mtriple=arm-unknown-eabi -mcpu=strongarm | FileCheck %s -check-prefix=ARM
+; RUN: llc < %s -mtriple=arm-unknown-eabi -mcpu=cortex-a8 | FileCheck %s -check-prefix=THUMB
+; RUN: llc < %s -mtriple=arm-unknown-eabi -mattr=+v6 | FileCheck %s -check-prefix=THUMB
+; RUN: llc < %s -mtriple=armv4-unknown-eabi | FileCheck %s -check-prefix=ARM
+; RUN: llc < %s -mtriple=armv4t-unknown-eabi | FileCheck %s -check-prefix=THUMB
+
+define arm_aapcscc i32 @test(i32 %a) nounwind readnone {
+entry:
+; ARM: mov pc
+; THUMB: bx
+  ret i32 %a
+}