Enable generating legacy IT block for AArch32

By default, the behavior of IT block generation will be determinated
dynamically base on the arch (armv8 vs armv7). This patch adds backend
options: -arm-restrict-it and -arm-no-restrict-it.  The former one
restricts the generation of IT blocks (the same behavior as thumbv8) for
both arches. The later one allows the generation of legacy IT block (the
same behavior as ARMv7 Thumb2) for both arches.

Clang will support -mrestrict-it and -mno-restrict-it, which is
compatible with GCC.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194592 91177308-0d34-0410-b5e6-96231b3b80d8

14 files changed, 57 insertions, 8 deletions

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 7187d6a..b76ef96 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -525,7 +525,7 @@ bool ARMBaseInstrInfo::isPredicable(MachineInstr *MI) const {
     MI->getParent()->getParent()->getInfo<ARMFunctionInfo>();
 
   if (AFI->isThumb2Function()) {
-    if (getSubtarget().hasV8Ops())
+    if (getSubtarget().restrictIT())
       return isV8EligibleForIT(MI);
   } else { // non-Thumb
     if ((MI->getDesc().TSFlags & ARMII::DomainMask) == ARMII::DomainNEON)
diff --git a/lib/Target/ARM/ARMSubtarget.cpp b/lib/Target/ARM/ARMSubtarget.cpp
index f59e522..a116298 100644
--- a/lib/Target/ARM/ARMSubtarget.cpp
+++ b/lib/Target/ARM/ARMSubtarget.cpp
@@ -57,6 +57,23 @@ Align(cl::desc("Load/store alignment support"),
                      "Allow unaligned memory accesses"),
           clEnumValEnd));
 
+enum ITMode {
+  DefaultIT,
+  RestrictedIT,
+  NoRestrictedIT
+};
+
+static cl::opt<ITMode>
+IT(cl::desc("IT block support"), cl::Hidden, cl::init(DefaultIT),
+   cl::ZeroOrMore,
+   cl::values(clEnumValN(DefaultIT, "arm-default-it",
+                         "Generate IT block based on arch"),
+              clEnumValN(RestrictedIT, "arm-restrict-it",
+                         "Disallow deprecated IT based on ARMv8"),
+              clEnumValN(NoRestrictedIT, "arm-no-restrict-it",
+                         "Allow IT blocks based on ARMv7"),
+              clEnumValEnd));
+
 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &CPU,
                            const std::string &FS, const TargetOptions &Options)
   : ARMGenSubtargetInfo(TT, CPU, FS)
@@ -217,6 +234,18 @@ void ARMSubtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
       break;
   }
 
+  switch (IT) {
+  case DefaultIT:
+    RestrictIT = hasV8Ops() ? true : false;
+    break;
+  case RestrictedIT:
+    RestrictIT = true;
+    break;
+  case NoRestrictedIT:
+    RestrictIT = false;
+    break;
+  }
+
   // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
   uint64_t Bits = getFeatureBits();
   if ((Bits & ARM::ProcA5 || Bits & ARM::ProcA8) && // Where this matters
diff --git a/lib/Target/ARM/ARMSubtarget.h b/lib/Target/ARM/ARMSubtarget.h
index aab93f1..5276901 100644
--- a/lib/Target/ARM/ARMSubtarget.h
+++ b/lib/Target/ARM/ARMSubtarget.h
@@ -177,6 +177,10 @@ protected:
   /// ARMTargetLowering::allowsUnalignedMemoryAccesses().
   bool AllowsUnalignedMem;
 
+  /// RestrictIT - If true, the subtarget disallows generation of deprecated IT
+  ///  blocks to conform to ARMv8 rule.
+  bool RestrictIT;
+
   /// Thumb2DSP - If true, the subtarget supports the v7 DSP (saturating arith
   /// and such) instructions in Thumb2 code.
   bool Thumb2DSP;
@@ -327,6 +331,8 @@ public:
 
   bool allowsUnalignedMem() const { return AllowsUnalignedMem; }
 
+  bool restrictIT() const { return RestrictIT; }
+
   const std::string & getCPUString() const { return CPUString; }
 
   unsigned getMispredictionPenalty() const;
diff --git a/lib/Target/ARM/ARMTargetMachine.cpp b/lib/Target/ARM/ARMTargetMachine.cpp
index c78db54..c2bf788 100644
--- a/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/lib/Target/ARM/ARMTargetMachine.cpp
@@ -198,7 +198,7 @@ bool ARMPassConfig::addPreSched2() {
   if (getOptLevel() != CodeGenOpt::None) {
     if (!getARMSubtarget().isThumb1Only()) {
       // in v8, IfConversion depends on Thumb instruction widths
-      if (getARMSubtarget().hasV8Ops() &&
+      if (getARMSubtarget().restrictIT() &&
           !getARMSubtarget().prefers32BitThumb())
         addPass(createThumb2SizeReductionPass());
       addPass(&IfConverterID);
diff --git a/lib/Target/ARM/Thumb2ITBlockPass.cpp b/lib/Target/ARM/Thumb2ITBlockPass.cpp
index 8f1ae2e..0b7d3bb 100644
--- a/lib/Target/ARM/Thumb2ITBlockPass.cpp
+++ b/lib/Target/ARM/Thumb2ITBlockPass.cpp
@@ -28,7 +28,7 @@ namespace {
     static char ID;
     Thumb2ITBlockPass() : MachineFunctionPass(ID) {}
 
-    bool hasV8Ops;
+    bool restrictIT;
     const Thumb2InstrInfo *TII;
     const TargetRegisterInfo *TRI;
     ARMFunctionInfo *AFI;
@@ -194,8 +194,9 @@ bool Thumb2ITBlockPass::InsertITInstructions(MachineBasicBlock &MBB) {
     ARMCC::CondCodes OCC = ARMCC::getOppositeCondition(CC);
     unsigned Mask = 0, Pos = 3;
 
-    // v8 IT blocks are limited to one conditional op: skip the loop
-    if (!hasV8Ops) {
+    // v8 IT blocks are limited to one conditional op unless -arm-no-restrict-it
+    // is set: skip the loop
+    if (!restrictIT) {
       // Branches, including tricky ones like LDM_RET, need to end an IT
       // block so check the instruction we just put in the block.
       for (; MBBI != E && Pos &&
@@ -255,7 +256,7 @@ bool Thumb2ITBlockPass::runOnMachineFunction(MachineFunction &Fn) {
   AFI = Fn.getInfo<ARMFunctionInfo>();
   TII = static_cast<const Thumb2InstrInfo*>(TM.getInstrInfo());
   TRI = TM.getRegisterInfo();
-  hasV8Ops = TM.getSubtarget<ARMSubtarget>().hasV8Ops();
+  restrictIT = TM.getSubtarget<ARMSubtarget>().restrictIT();
 
   if (!AFI->isThumbFunction())
     return false;
diff --git a/test/CodeGen/ARM/2013-05-05-IfConvertBug.ll b/test/CodeGen/ARM/2013-05-05-IfConvertBug.ll
index 2bebcf4..c4f5f54 100644
--- a/test/CodeGen/ARM/2013-05-05-IfConvertBug.ll
+++ b/test/CodeGen/ARM/2013-05-05-IfConvertBug.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -mtriple=thumbv7-apple-ios -mcpu=cortex-a8 | FileCheck %s
 ; RUN: llc < %s -mtriple=thumbv8 | FileCheck -check-prefix=CHECK-V8 %s
+; RUN: llc < %s -mtriple=thumbv7 -arm-restrict-it | FileCheck -check-prefix=CHECK-V8 %s
 ; rdar://13782395
 
 define i32 @t1(i32 %a, i32 %b, i8** %retaddr) {
diff --git a/test/CodeGen/Thumb2/thumb2-ifcvt1.ll b/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
index 85943cf..13a1ca2 100644
--- a/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
+++ b/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
-
+; RUN: llc < %s -mtriple=thumbv7-apple-darwin -arm-default-it | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv8 -arm-no-restrict-it |FileCheck %s
 define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
 ; CHECK-LABEL: t1:
 ; CHECK: ittt ne
@@ -74,7 +75,7 @@ entry:
 ; CHECK-LABEL: t3:
 ; CHECK: itt ge
 ; CHECK: movge r0, r1
-; CHECK: blge  _foo
+; CHECK: blge  {{_?}}foo
 	%tmp1 = icmp sgt i32 %a, 10		; <i1> [#uses=1]
 	br i1 %tmp1, label %cond_true, label %UnifiedReturnBlock
 
diff --git a/test/CodeGen/Thumb2/thumb2-ifcvt2.ll b/test/CodeGen/Thumb2/thumb2-ifcvt2.ll
index 788fa06..403cd48 100644
--- a/test/CodeGen/Thumb2/thumb2-ifcvt2.ll
+++ b/test/CodeGen/Thumb2/thumb2-ifcvt2.ll
@@ -1,4 +1,6 @@
 ; RUN: llc < %s -mtriple=thumbv7-apple-ios | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7-apple-ios -arm-default-it | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv8-apple-ios -arm-no-restrict-it | FileCheck %s
 
 define void @foo(i32 %X, i32 %Y) {
 entry:
diff --git a/test/CodeGen/Thumb2/thumb2-ifcvt3.ll b/test/CodeGen/Thumb2/thumb2-ifcvt3.ll
index bcf10ef..a71aa3f 100644
--- a/test/CodeGen/Thumb2/thumb2-ifcvt3.ll
+++ b/test/CodeGen/Thumb2/thumb2-ifcvt3.ll
@@ -1,4 +1,6 @@
 ; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7-apple-darwin -arm-default-it | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv8-apple-darwin -arm-no-restrict-it | FileCheck %s
 
 ; There shouldn't be a unconditional branch at end of bb52.
 ; rdar://7184787
diff --git a/test/CodeGen/Thumb2/v8_IT_1.ll b/test/CodeGen/Thumb2/v8_IT_1.ll
index 9248378..30dbb48 100644
--- a/test/CodeGen/Thumb2/v8_IT_1.ll
+++ b/test/CodeGen/Thumb2/v8_IT_1.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -mtriple=thumbv8 -mattr=+neon | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7 -mattr=+neon -arm-restrict-it | FileCheck %s
 
 ;CHECK-LABEL: select_s_v_v:
 ;CHECK-NOT: it
diff --git a/test/CodeGen/Thumb2/v8_IT_2.ll b/test/CodeGen/Thumb2/v8_IT_2.ll
index fe88316..170b413 100644
--- a/test/CodeGen/Thumb2/v8_IT_2.ll
+++ b/test/CodeGen/Thumb2/v8_IT_2.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -mtriple=thumbv8 | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7 -arm-restrict-it | FileCheck %s
 
 	%struct.quad_struct = type { i32, i32, %struct.quad_struct*, %struct.quad_struct*, %struct.quad_struct*, %struct.quad_struct*, %struct.quad_struct* }
 
diff --git a/test/CodeGen/Thumb2/v8_IT_3.ll b/test/CodeGen/Thumb2/v8_IT_3.ll
index 4d90891..4dca246 100644
--- a/test/CodeGen/Thumb2/v8_IT_3.ll
+++ b/test/CodeGen/Thumb2/v8_IT_3.ll
@@ -1,5 +1,7 @@
 ; RUN: llc < %s -mtriple=thumbv8 | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7 -arm-restrict-it | FileCheck %s
 ; RUN: llc < %s -mtriple=thumbv8 -relocation-model=pic | FileCheck %s --check-prefix=CHECK-PIC
+; RUN: llc < %s -mtriple=thumbv7 -arm-restrict-it -relocation-model=pic | FileCheck %s --check-prefix=CHECK-PIC
 
 %struct.FF = type { i32 (i32*)*, i32 (i32*, i32*, i32, i32, i32, i32)*, i32 (i32, i32, i8*)*, void ()*, i32 (i32, i8*, i32*)*, i32 ()* }
 %struct.BD = type { %struct.BD*, i32, i32, i32, i32, i64, i32 (%struct.BD*, i8*, i64, i32)*, i32 (%struct.BD*, i8*, i32, i32)*, i32 (%struct.BD*, i8*, i64, i32)*, i32 (%struct.BD*, i8*, i32, i32)*, i32 (%struct.BD*, i64, i32)*, [16 x i8], i64, i64 }
diff --git a/test/CodeGen/Thumb2/v8_IT_4.ll b/test/CodeGen/Thumb2/v8_IT_4.ll
index 45c79f4..5a80d8c 100644
--- a/test/CodeGen/Thumb2/v8_IT_4.ll
+++ b/test/CodeGen/Thumb2/v8_IT_4.ll
@@ -1,5 +1,7 @@
 ; RUN: llc < %s -mtriple=thumbv8-eabi -float-abi=hard | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7-eabi -float-abi=hard -arm-restrict-it | FileCheck %s
 ; RUN: llc < %s -mtriple=thumbv8-eabi -float-abi=hard -regalloc=basic | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7-eabi -float-abi=hard -regalloc=basic -arm-restrict-it | FileCheck %s
 
 %"struct.__gnu_cxx::__normal_iterator<char*,std::basic_string<char, std::char_traits<char>, std::allocator<char> > >" = type { i8* }
 %"struct.__gnu_cxx::new_allocator<char>" = type <{ i8 }>
diff --git a/test/CodeGen/Thumb2/v8_IT_5.ll b/test/CodeGen/Thumb2/v8_IT_5.ll
index 3866068..30250c8 100644
--- a/test/CodeGen/Thumb2/v8_IT_5.ll
+++ b/test/CodeGen/Thumb2/v8_IT_5.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -mtriple=thumbv8 | FileCheck %s
+; RUN: llc < %s -mtriple=thumbv7 -arm-restrict-it | FileCheck %s
 ; CHECK: it	ne
 ; CHECK-NEXT: cmpne
 ; CHECK-NEXT: beq