Revert rL342465: Added function to set a register to a particular value + tests.

rL342465 is breaking the MSVC buildbots.

llvm-svn: 342490
diff --git a/llvm/tools/llvm-exegesis/lib/X86/Target.cpp b/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
index e682b98..e55e77d 100644
--- a/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
+++ b/llvm/tools/llvm-exegesis/lib/X86/Target.cpp
@@ -115,9 +115,7 @@
   llvm_unreachable("Invalid Value Width");
 }
 
-static llvm::MCInst loadImmediate(unsigned Reg, const llvm::APInt &Value,
-                                  unsigned MaxBitWidth) {
-  assert(Value.getBitWidth() <= MaxBitWidth && "Value too big to fit register");
+static llvm::MCInst loadImmediate(unsigned Reg, const llvm::APInt &Value) {
   return llvm::MCInstBuilder(GetLoadImmediateOpcode(Value))
       .addReg(Reg)
       .addImm(Value.getZExtValue());
@@ -169,59 +167,35 @@
   explicit ConstantInliner(const llvm::APInt &Constant)
       : StackSize(Constant.getBitWidth() / 8) {
     assert(Constant.getBitWidth() % 8 == 0 && "Must be a multiple of 8");
-    add(allocateStackSpace(StackSize));
+    Add(allocateStackSpace(StackSize));
     size_t ByteOffset = 0;
     for (; StackSize - ByteOffset >= 4; ByteOffset += 4)
-      add(fillStackSpace(
+      Add(fillStackSpace(
           llvm::X86::MOV32mi, ByteOffset,
           Constant.extractBits(32, ByteOffset * 8).getZExtValue()));
     if (StackSize - ByteOffset >= 2) {
-      add(fillStackSpace(
+      Add(fillStackSpace(
           llvm::X86::MOV16mi, ByteOffset,
           Constant.extractBits(16, ByteOffset * 8).getZExtValue()));
       ByteOffset += 2;
     }
     if (StackSize - ByteOffset >= 1)
-      add(fillStackSpace(
+      Add(fillStackSpace(
           llvm::X86::MOV8mi, ByteOffset,
           Constant.extractBits(8, ByteOffset * 8).getZExtValue()));
   }
 
-  std::vector<llvm::MCInst> loadAndFinalize(unsigned Reg, unsigned Opcode,
-                                            unsigned BitWidth) {
-    assert(StackSize * 8 == BitWidth && "Value does not have the correct size");
-    add(loadToReg(Reg, Opcode));
-    add(releaseStackSpace(StackSize));
-    return std::move(Instructions);
-  }
-
-  std::vector<llvm::MCInst> loadX87AndFinalize(unsigned Reg, unsigned Opcode,
-                                               unsigned BitWidth) {
-    assert(StackSize * 8 == BitWidth && "Value does not have the correct size");
-    add(llvm::MCInstBuilder(Opcode)
-            .addReg(llvm::X86::RSP) // BaseReg
-            .addImm(1)              // ScaleAmt
-            .addReg(0)              // IndexReg
-            .addImm(0)              // Disp
-            .addReg(0));            // Segment
-    if (Reg != llvm::X86::ST0)
-      add(llvm::MCInstBuilder(llvm::X86::ST_Frr).addReg(Reg));
-    add(releaseStackSpace(StackSize));
-    return std::move(Instructions);
-  }
-
-  std::vector<llvm::MCInst> popFlagAndFinalize() {
-    assert(StackSize * 8 == 32 && "Value does not have the correct size");
-    add(llvm::MCInstBuilder(llvm::X86::POPF64));
-    return std::move(Instructions);
-  }
-
-private:
-  ConstantInliner &add(const llvm::MCInst &Inst) {
+  ConstantInliner &Add(const llvm::MCInst &Inst) {
     Instructions.push_back(Inst);
     return *this;
   }
 
+  std::vector<llvm::MCInst> finalize() {
+    Add(releaseStackSpace(StackSize));
+    return std::move(Instructions);
+  }
+
+private:
   const size_t StackSize;
   std::vector<llvm::MCInst> Instructions;
 };
@@ -274,46 +248,63 @@
     }
   }
 
-  std::vector<llvm::MCInst> setRegTo(const llvm::MCSubtargetInfo &STI,
-                                     const llvm::APInt &Value,
-                                     unsigned Reg) const override {
+  std::vector<llvm::MCInst> setRegToConstant(const llvm::MCSubtargetInfo &STI,
+                                             unsigned Reg) const override {
+    // GPR.
     if (llvm::X86::GR8RegClass.contains(Reg))
-      return {loadImmediate(Reg, Value, 8)};
+      return {llvm::MCInstBuilder(llvm::X86::MOV8ri).addReg(Reg).addImm(1)};
     if (llvm::X86::GR16RegClass.contains(Reg))
-      return {loadImmediate(Reg, Value, 16)};
+      return {llvm::MCInstBuilder(llvm::X86::MOV16ri).addReg(Reg).addImm(1)};
     if (llvm::X86::GR32RegClass.contains(Reg))
-      return {loadImmediate(Reg, Value, 32)};
+      return {llvm::MCInstBuilder(llvm::X86::MOV32ri).addReg(Reg).addImm(1)};
     if (llvm::X86::GR64RegClass.contains(Reg))
-      return {loadImmediate(Reg, Value, 64)};
-    ConstantInliner CI(Value);
+      return {llvm::MCInstBuilder(llvm::X86::MOV64ri32).addReg(Reg).addImm(1)};
+    // MMX.
     if (llvm::X86::VR64RegClass.contains(Reg))
-      return CI.loadAndFinalize(Reg, llvm::X86::MMX_MOVQ64rm, 64);
+      return setVectorRegToConstant(Reg, 8, llvm::X86::MMX_MOVQ64rm);
+    // {X,Y,Z}MM.
     if (llvm::X86::VR128XRegClass.contains(Reg)) {
       if (STI.getFeatureBits()[llvm::X86::FeatureAVX512])
-        return CI.loadAndFinalize(Reg, llvm::X86::VMOVDQU32Z128rm, 128);
+        return setVectorRegToConstant(Reg, 16, llvm::X86::VMOVDQU32Z128rm);
       if (STI.getFeatureBits()[llvm::X86::FeatureAVX])
-        return CI.loadAndFinalize(Reg, llvm::X86::VMOVDQUrm, 128);
-      return CI.loadAndFinalize(Reg, llvm::X86::MOVDQUrm, 128);
+        return setVectorRegToConstant(Reg, 16, llvm::X86::VMOVDQUrm);
+      return setVectorRegToConstant(Reg, 16, llvm::X86::MOVDQUrm);
     }
     if (llvm::X86::VR256XRegClass.contains(Reg)) {
       if (STI.getFeatureBits()[llvm::X86::FeatureAVX512])
-        return CI.loadAndFinalize(Reg, llvm::X86::VMOVDQU32Z256rm, 256);
-      if (STI.getFeatureBits()[llvm::X86::FeatureAVX])
-        return CI.loadAndFinalize(Reg, llvm::X86::VMOVDQUYrm, 256);
+        return setVectorRegToConstant(Reg, 32, llvm::X86::VMOVDQU32Z256rm);
+      return setVectorRegToConstant(Reg, 32, llvm::X86::VMOVDQUYrm);
     }
     if (llvm::X86::VR512RegClass.contains(Reg))
-      if (STI.getFeatureBits()[llvm::X86::FeatureAVX512])
-        return CI.loadAndFinalize(Reg, llvm::X86::VMOVDQU32Zrm, 512);
-    if (llvm::X86::RSTRegClass.contains(Reg)) {
-      if (Value.getBitWidth() == 32)
-        return CI.loadX87AndFinalize(Reg, llvm::X86::LD_F32m, 32);
-      if (Value.getBitWidth() == 64)
-        return CI.loadX87AndFinalize(Reg, llvm::X86::LD_F64m, 64);
-      if (Value.getBitWidth() == 80)
-        return CI.loadX87AndFinalize(Reg, llvm::X86::LD_F80m, 80);
+      return setVectorRegToConstant(Reg, 64, llvm::X86::VMOVDQU32Zrm);
+    // X87.
+    if (llvm::X86::RFP32RegClass.contains(Reg) ||
+        llvm::X86::RFP64RegClass.contains(Reg) ||
+        llvm::X86::RFP80RegClass.contains(Reg))
+      return setVectorRegToConstant(Reg, 8, llvm::X86::LD_Fp64m);
+    if (Reg == llvm::X86::EFLAGS) {
+      // Set all flags to 0 but the bits that are "reserved and set to 1".
+      constexpr const uint32_t kImmValue = 0x00007002u;
+      std::vector<llvm::MCInst> Result;
+      Result.push_back(allocateStackSpace(8));
+      Result.push_back(fillStackSpace(llvm::X86::MOV64mi32, 0, kImmValue));
+      Result.push_back(llvm::MCInstBuilder(llvm::X86::POPF64)); // Also pops.
+      return Result;
     }
-    if (Reg == llvm::X86::EFLAGS)
-      return CI.popFlagAndFinalize();
+    llvm_unreachable("Not yet implemented");
+  }
+
+  std::vector<llvm::MCInst> setRegTo(const llvm::MCSubtargetInfo &STI,
+                                     const llvm::APInt &Value,
+                                     unsigned Reg) const override {
+    if (llvm::X86::GR8RegClass.contains(Reg) ||
+        llvm::X86::GR16RegClass.contains(Reg) ||
+        llvm::X86::GR32RegClass.contains(Reg) ||
+        llvm::X86::GR64RegClass.contains(Reg))
+      return {loadImmediate(Reg, Value)};
+    ConstantInliner CI(Value);
+    if (llvm::X86::VR64RegClass.contains(Reg))
+      return CI.Add(loadToReg(Reg, llvm::X86::MMX_MOVQ64rm)).finalize();
     llvm_unreachable("Not yet implemented");
   }
 
@@ -330,6 +321,31 @@
   bool matchesArch(llvm::Triple::ArchType Arch) const override {
     return Arch == llvm::Triple::x86_64 || Arch == llvm::Triple::x86;
   }
+
+private:
+  // setRegToConstant() specialized for a vector register of size
+  // `RegSizeBytes`. `RMOpcode` is the opcode used to do a memory -> vector
+  // register load.
+  static std::vector<llvm::MCInst>
+  setVectorRegToConstant(const unsigned Reg, const unsigned RegSizeBytes,
+                         const unsigned RMOpcode) {
+    // There is no instruction to directly set XMM, go through memory.
+    // Since vector values can be interpreted as integers of various sizes (8
+    // to 64 bits) as well as floats and double, so we chose an immediate
+    // value that has set bits for all byte values and is a normal float/
+    // double. 0x40404040 is ~32.5 when interpreted as a double and ~3.0f when
+    // interpreted as a float.
+    constexpr const uint32_t kImmValue = 0x40404040u;
+    std::vector<llvm::MCInst> Result;
+    Result.push_back(allocateStackSpace(RegSizeBytes));
+    constexpr const unsigned kMov32NumBytes = 4;
+    for (unsigned Disp = 0; Disp < RegSizeBytes; Disp += kMov32NumBytes) {
+      Result.push_back(fillStackSpace(llvm::X86::MOV32mi, Disp, kImmValue));
+    }
+    Result.push_back(loadToReg(Reg, RMOpcode));
+    Result.push_back(releaseStackSpace(RegSizeBytes));
+    return Result;
+  }
 };
 
 } // namespace