Implement FastMaterializeAlloca in Mips fast-isel

[vkalintiris]

Summary

Implement the method FastMaterializeAlloca in Mips fast-isel

[vkalintiris]

Add explicit type parameter to load/GEP instructions.

[dsanders]

LGTM with some changes

lib/Target/Mips/MipsFastISel.cpp

265–268

This is redundant. DenseMapBase<...>::find() returns DenseMapBase<...>::end() when the key isn't found so there's no need to separately count(AI) and find(AI)

test/CodeGen/Mips/Fast-ISel/fastalloca.ll

3–6

Please drop these four lines from the test. It's better to specify the triple on the command line and using the default datalayout will be better if it ever needs to change.

5–8

Please drop these four lines from the test. It's better to specify the triple on the command line and using the default datalayout will be better if it ever needs to change.

(sorry for the duplicate comment, Phabricator won't let me delete either of them for some reason)

17–30

I think we could simplify this test quite a lot. We only want to test alloca instructions so I think we could do something like:

define i32 @foo(i32* %d) {
  %0 = alloca i32, align 4
  store i32 %0, i32* %d, align 4
}

and just check that appropriate addiu's and sw's are created. Obviously, we'd want to test a few layouts.

That said, we've discussed (off-list) your plan to migrate these tests to a style similar to the test/CodeGen/Mips/llvm-ir tests (which tries to test each LLVM-IR instruction with as few dependencies as possible) once the backlog is cleared and I'm happy for this kind of change to be made at that point.

32

Nit: indentation

40–58

Nit: Not needed.

lib/Target/Mips/MipsFastISel.cpp

explicit MipsFastISel(FunctionLoweringInfo &funcInfo,
     MFI = funcInfo.MF->getInfo<MipsFunctionInfo>();
     Context = &funcInfo.Fn->getContext();
     TargetSupported = ((Subtarget->getRelocationModel() == Reloc::PIC_) &&
                        ((Subtarget->hasMips32r2() || Subtarget->hasMips32()) &&
                         (Subtarget->isABI_O32())));
     UnsupportedFPMode = Subtarget->isFP64bit();
   }
 
+  unsigned fastMaterializeAlloca(const AllocaInst *AI) override;
   unsigned fastMaterializeConstant(const Constant *C) override;
   bool fastSelectInstruction(const Instruction *I) override;
 
 #include "MipsGenFastISel.inc"
 };
 } // end anonymous namespace.
 
 static bool CC_Mips(unsigned ValNo, MVT ValVT, MVT LocVT,
unsigned MipsFastISel::emitLogicalOp(unsigned ISDOpc, MVT RetVT,
   else
     RHSReg = getRegForValue(RHS);
   if (!RHSReg)
     return 0;
   emitInst(Opc, ResultReg).addReg(LHSReg).addReg(RHSReg);
   return ResultReg;
 }
 
+unsigned MipsFastISel::fastMaterializeAlloca(const AllocaInst *AI) {
+  assert(TLI.getValueType(AI->getType(), true) == MVT::i32 &&
+         "Alloca should always return a pointer.");
+
+  // Don't handle dynamic allocas.
+  if (!FuncInfo.StaticAllocaMap.count(AI))
+    return 0;
+
+  DenseMap<const AllocaInst *, int>::iterator SI =
+      FuncInfo.StaticAllocaMap.find(AI);
+
+  if (SI != FuncInfo.StaticAllocaMap.end()) {
+    unsigned ResultReg = createResultReg(&Mips::GPR32RegClass);
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Mips::LEA_ADDiu),
+            ResultReg)
+        .addFrameIndex(SI->second)
+        .addImm(0);
+    return ResultReg;
+  }
+
+  return 0;
+}
+
 unsigned MipsFastISel::materializeInt(const Constant *C, MVT VT) {
   if (VT != MVT::i32 && VT != MVT::i16 && VT != MVT::i8 && VT != MVT::i1)
     return 0;
   const TargetRegisterClass *RC = &Mips::GPR32RegClass;
   const ConstantInt *CI = cast<ConstantInt>(C);
   int64_t Imm;
   if ((VT != MVT::i1) && CI->isNegative())
     Imm = CI->getSExtValue();

test/CodeGen/Mips/Fast-ISel/fastalloca.ll

+; RUN: llc -march=mipsel -relocation-model=pic -O0 -mips-fast-isel -fast-isel-abort -mcpu=mips32r2 \
+; RUN:     < %s | FileCheck %s
+
+; ModuleID = 'fooa.c'
+target datalayout = "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64"
+target triple = "mipsel--linux-gnu"
+
+%struct.x = type { i32 }
+
+@i = common global i32 0, align 4
+
+; Function Attrs: nounwind
+define i32 @foobar(i32 signext %x) #0 {
+entry:
+; CHECK-LABEL: foobar:
+  %retval = alloca i32, align 4
+  %x.addr = alloca i32, align 4
+  %a = alloca %struct.x, align 4
+  %c = alloca %struct.x*, align 4
+  store i32 %x, i32* %x.addr, align 4
+  %x1 = getelementptr inbounds %struct.x* %a, i32 0, i32 0
+  %0 = load i32* %x.addr, align 4
+  store i32 %0, i32* %x1, align 4
+  store %struct.x* %a, %struct.x** %c, align 4
+  %1 = load %struct.x** %c, align 4
+  %x2 = getelementptr inbounds %struct.x* %1, i32 0, i32 0
+  %2 = load i32* %x2, align 4
+  store i32 %2, i32* @i, align 4
+  %3 = load i32* %retval
+; CHECK-DAG:  lw  $[[I_ADDR:[0-9]+]], %got(i)($[[REG_GP:[0-9]+]])
+; CHECK-DAG:  addiu $[[A_ADDR:[0-9]+]], $fp, 8
+; CHECK-DAG:    sw      $[[A_ADDR]], [[A_ADDR_FI:[0-9]+]]($fp)
+; CHECK-DAG:    lw      $[[A_ADDR2:[0-9]+]], [[A_ADDR_FI]]($fp)
+; CHECK-DAG:    lw      $[[A_X:[0-9]+]], 0($[[A_ADDR2]])
+; CHECK-DAG:    sw      $[[A_X]], 0($[[I_ADDR]]) 
+  ret i32 %3
+}
+
+; Function Attrs: nounwind
+define i32 @main() #0 {
+entry:
+; CHECK-LABEL: main:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval
+  %call = call i32 @foobar(i32 signext 99)
+  %0 = load i32* @i, align 4
+  %sub = sub nsw i32 99, %0
+  ret i32 %sub
+}
+
+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" }
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+!0 = !{i32 1, !"PIC Level", i32 2}
+!1 = !{!"clang version 3.6.0 ([e-mail]:clang.git f96fd4c68e89695cc64686bcf0dc768aee4638e5) ([e-mail]:llvm.git 33df92e7a51bb034540e4de79d2d4cff83439d7b)"}

test/CodeGen/Mips/Fast-ISel/logopm.ll

 
 ; Function Attrs: noreturn
 declare void @abort() #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" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
 attributes #1 = { noreturn "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 #2 = { noreturn }
 
-!llvm.module.flags = !{!0}
-!llvm.ident = !{!1}
 
-!0 = metadata !{i32 1, metadata !"PIC Level", i32 2}
-!1 = metadata !{metadata !"clang version 3.6.0 ([e-mail]:clang.git 59d05423ef08bc76eeedb88bb7bfa0b0e0415711) ([e-mail]:llvm.git 431113b8f2ea22b437e86d06a0ce5fbe78e2d4cb)"}