[llvm] r218492 - Add the first backend support for on demand subtarget creation

Eric Christopher echristo at gmail.com
Thu Sep 25 18:44:09 PDT 2014


Author: echristo
Date: Thu Sep 25 20:44:08 2014
New Revision: 218492

URL: http://llvm.org/viewvc/llvm-project?rev=218492&view=rev
Log:
Add the first backend support for on demand subtarget creation
based on the Function. This is currently used to implement
mips16 support in the mips backend via the existing module
pass resetting the subtarget.

Things to note:

a) This involved running resetTargetOptions before creating a
new subtarget so that code generation options like soft-float
could be recognized when creating the new subtarget. This is
to deal with initialization code in isel lowering that only
paid attention to the initial value.

b) Many of the existing testcases weren't using the soft-float
feature correctly. I've corrected these based on the check
values assuming that was the desired behavior.

c) The mips port now pays attention to the target-cpu and
target-features strings when generating code for a particular
function. I've removed these from one function where the
requested cpu and features didn't match the check lines in
the testcase.

Modified:
    llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp
    llvm/trunk/lib/Target/Mips/MipsTargetMachine.h
    llvm/trunk/test/CodeGen/Mips/fp16instrinsmc.ll
    llvm/trunk/test/CodeGen/Mips/hfptrcall.ll
    llvm/trunk/test/CodeGen/Mips/nomips16.ll
    llvm/trunk/test/CodeGen/Mips/seleq.ll

Modified: llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp?rev=218492&r1=218491&r2=218492&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/Mips/MipsTargetMachine.cpp Thu Sep 25 20:44:08 2014
@@ -56,7 +56,8 @@ MipsTargetMachine::MipsTargetMachine(con
                                      Reloc::Model RM, CodeModel::Model CM,
                                      CodeGenOpt::Level OL, bool isLittle)
     : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
-      Subtarget(nullptr), DefaultSubtarget(TT, CPU, FS, isLittle, this),
+      isLittle(isLittle), Subtarget(nullptr),
+      DefaultSubtarget(TT, CPU, FS, isLittle, this),
       NoMips16Subtarget(TT, CPU, FS.empty() ? "-mips16" : FS.str() + ",-mips16",
                         isLittle, this),
       Mips16Subtarget(TT, CPU, FS.empty() ? "+mips16" : FS.str() + ",+mips16",
@@ -83,20 +84,47 @@ MipselTargetMachine(const Target &T, Str
                     CodeGenOpt::Level OL)
   : MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, true) {}
 
+const MipsSubtarget *
+MipsTargetMachine::getSubtargetImpl(const Function &F) const override {
+  AttributeSet FnAttrs = F.getAttributes();
+  Attribute CPUAttr =
+      FnAttrs.getAttribute(AttributeSet::FunctionIndex, "target-cpu");
+  Attribute FSAttr =
+      FnAttrs.getAttribute(AttributeSet::FunctionIndex, "target-features");
+
+  std::string CPU = !CPUAttr.hasAttribute(Attribute::None)
+                        ? CPUAttr.getValueAsString().str()
+                        : TargetCPU;
+  std::string FS = !FSAttr.hasAttribute(Attribute::None)
+                       ? FSAttr.getValueAsString().str()
+                       : TargetFS;
+  bool hasMips16Attr =
+      !FnAttrs.getAttribute(AttributeSet::FunctionIndex, "mips16")
+           .hasAttribute(Attribute::None);
+  bool hasNoMips16Attr =
+      !FnAttrs.getAttribute(AttributeSet::FunctionIndex, "nomips16")
+           .hasAttribute(Attribute::None);
+
+  if (hasMips16Attr)
+    FS += FS.empty() ? "+mips16" : ",+mips16";
+  else if (hasNoMips16Attr)
+    FS += FS.empty() ? "-mips16" : ",-mips16";
+
+  auto &I = SubtargetMap[CPU + FS];
+  if (!I) {
+    // This needs to be done before we create a new subtarget since any
+    // creation will depend on the TM and the code generation flags on the
+    // function that reside in TargetOptions.
+    resetTargetOptions(F);
+    I = make_unique<MipsSubtarget>(TargetTriple, CPU, FS, isLittle, this);
+  }
+  return I.get();
+}
+
 void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {
   DEBUG(dbgs() << "resetSubtarget\n");
-  AttributeSet FnAttrs = MF->getFunction()->getAttributes();
-  bool Mips16Attr = FnAttrs.hasAttribute(AttributeSet::FunctionIndex, "mips16");
-  bool NoMips16Attr =
-      FnAttrs.hasAttribute(AttributeSet::FunctionIndex, "nomips16");
-  assert(!(Mips16Attr && NoMips16Attr) &&
-         "mips16 and nomips16 specified on the same function");
-  if (Mips16Attr)
-    Subtarget = &Mips16Subtarget;
-  else if (NoMips16Attr)
-    Subtarget = &NoMips16Subtarget;
-  else
-    Subtarget = &DefaultSubtarget;
+
+  Subtarget = const_cast<MipsSubtarget*>(getSubtargetImpl(MF->getFunction()));
   MF->setSubtarget(Subtarget);
   return;
 }

Modified: llvm/trunk/lib/Target/Mips/MipsTargetMachine.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/MipsTargetMachine.h?rev=218492&r1=218491&r2=218492&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/MipsTargetMachine.h (original)
+++ llvm/trunk/lib/Target/Mips/MipsTargetMachine.h Thu Sep 25 20:44:08 2014
@@ -25,11 +25,14 @@ class formatted_raw_ostream;
 class MipsRegisterInfo;
 
 class MipsTargetMachine : public LLVMTargetMachine {
+  bool isLittle;
   MipsSubtarget *Subtarget;
   MipsSubtarget DefaultSubtarget;
   MipsSubtarget NoMips16Subtarget;
   MipsSubtarget Mips16Subtarget;
 
+  mutable StringMap<std::unique_ptr<MipsSubtarget>> SubtargetMap;
+
 public:
   MipsTargetMachine(const Target &T, StringRef TT, StringRef CPU, StringRef FS,
                     const TargetOptions &Options, Reloc::Model RM,
@@ -45,6 +48,8 @@ public:
     return &DefaultSubtarget;
   }
 
+  const MipsSubtarget *getSubtargetImpl(const Function &F) const override;
+
   /// \brief Reset the subtarget for the Mips target.
   void resetSubtarget(MachineFunction *MF);
 

Modified: llvm/trunk/test/CodeGen/Mips/fp16instrinsmc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/fp16instrinsmc.ll?rev=218492&r1=218491&r2=218492&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/fp16instrinsmc.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/fp16instrinsmc.ll Thu Sep 25 20:44:08 2014
@@ -385,7 +385,7 @@ entry:
 ; Function Attrs: nounwind
 declare double @exp2(double) #0
 
-attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="true" }
+attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
 attributes #1 = { nounwind readnone "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="true" }
 attributes #2 = { nounwind readnone }
 attributes #3 = { nounwind }

Modified: llvm/trunk/test/CodeGen/Mips/hfptrcall.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/hfptrcall.ll?rev=218492&r1=218491&r2=218492&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/hfptrcall.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/hfptrcall.ll Thu Sep 25 20:44:08 2014
@@ -118,8 +118,8 @@ entry:
 
 declare i32 @printf(i8*, ...) #1
 
-attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="true" }
-attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="true" }
+attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
 
 
 

Modified: llvm/trunk/test/CodeGen/Mips/nomips16.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/nomips16.ll?rev=218492&r1=218491&r2=218492&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/nomips16.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/nomips16.ll Thu Sep 25 20:44:08 2014
@@ -33,6 +33,6 @@ entry:
 ; CHECK: 	.end	nofoo
 
 
-attributes #0 = { nounwind "less-precise-fpmad"="false" "mips16" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="true" }
-attributes #1 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "nomips16" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="true" }
+attributes #0 = { nounwind "less-precise-fpmad"="false" "mips16" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "nomips16" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
 

Modified: llvm/trunk/test/CodeGen/Mips/seleq.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/seleq.ll?rev=218492&r1=218491&r2=218492&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/seleq.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/seleq.ll Thu Sep 25 20:44:08 2014
@@ -10,7 +10,7 @@
 @z3 = common global i32 0, align 4
 @z4 = common global i32 0, align 4
 
-define void @calc_seleq() nounwind "target-cpu"="mips32" "target-features"="+o32,+mips32" {
+define void @calc_seleq() nounwind {
 entry:
   %0 = load i32* @a, align 4
   %1 = load i32* @b, align 4





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