[GlobalISel] Translate calls to memcpy et al to G_INTRINSIC_W_SIDE_EFFECTs and legalize later.

I plan on adding memcpy optimizations in the GlobalISel pipeline, but we can't
do that unless we delay lowering to actual function calls. This patch changes
the translator to generate G_INTRINSIC_W_SIDE_EFFECTS for these functions, and
then have each target specify that using the new custom legalizer for intrinsics
hook that they want it expanded it a libcall.

Differential Revision: https://reviews.llvm.org/D64895

llvm-svn: 366516

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/AArch64LegalizerInfo.cpp
index a985b330eaf..d54491532d6 100644
--- a/llvm/lib/Target/AArch64/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64LegalizerInfo.cpp
@@ -13,7 +13,9 @@
 
 #include "AArch64LegalizerInfo.h"
 #include "AArch64Subtarget.h"
+#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/CodeGen/GlobalISel/Utils.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetOpcodes.h"
@@ -617,6 +619,24 @@ bool AArch64LegalizerInfo::legalizeCustom(MachineInstr &MI,
   llvm_unreachable("expected switch to return");
 }
 
+bool AArch64LegalizerInfo::legalizeIntrinsic(
+    MachineInstr &MI, MachineRegisterInfo &MRI,
+    MachineIRBuilder &MIRBuilder) const {
+  switch (MI.getIntrinsicID()) {
+  case Intrinsic::memcpy:
+  case Intrinsic::memset:
+  case Intrinsic::memmove:
+    if (createMemLibcall(MIRBuilder, MRI, MI) ==
+        LegalizerHelper::UnableToLegalize)
+      return false;
+    MI.eraseFromParent();
+    return true;
+  default:
+    break;
+  }
+  return true;
+}
+
 bool AArch64LegalizerInfo::legalizeShlAshrLshr(
     MachineInstr &MI, MachineRegisterInfo &MRI, MachineIRBuilder &MIRBuilder,
     GISelChangeObserver &Observer) const {
diff --git a/llvm/lib/Target/AArch64/AArch64LegalizerInfo.h b/llvm/lib/Target/AArch64/AArch64LegalizerInfo.h
index f3362a18620..15161bab466 100644
--- a/llvm/lib/Target/AArch64/AArch64LegalizerInfo.h
+++ b/llvm/lib/Target/AArch64/AArch64LegalizerInfo.h
@@ -31,6 +31,9 @@ public:
                       MachineIRBuilder &MIRBuilder,
                       GISelChangeObserver &Observer) const override;
 
+  bool legalizeIntrinsic(MachineInstr &MI, MachineRegisterInfo &MRI,
+                         MachineIRBuilder &MIRBuilder) const override;
+
 private:
   bool legalizeVaArg(MachineInstr &MI, MachineRegisterInfo &MRI,
                      MachineIRBuilder &MIRBuilder) const;