[GISel] Add combiners for G_INTTOPTR and G_PTRTOINT

https://reviews.llvm.org/D84909

Patch adds two new GICombinerRules, one for G_INTTOPTR and one for
G_PTRTOINT. The G_INTTOPTR elides ptr2int(int2ptr(x)) to a copy of x, if
the cast is within the same address space. The G_PTRTOINT elides
int2ptr(ptr2int(x)) to a copy of x. Patch additionally adds new combiner
tests for the AArch64 target to test these new combiner rules.

Patch by mkitzan

diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
index e694e7a..3847112 100644 (file)
--- a/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
@@ -200,6 +200,14 @@ public:
   bool applyCombineShiftToUnmerge(MachineInstr &MI, const unsigned &ShiftVal);
   bool tryCombineShiftToUnmerge(MachineInstr &MI, unsigned TargetShiftAmount);
 
+  /// Transform IntToPtr(PtrToInt(x)) to x if cast is in the same address space.
+  bool matchCombineI2PToP2I(MachineInstr &MI, Register &Reg);
+  bool applyCombineI2PToP2I(MachineInstr &MI, Register &Reg);
+
+  /// Transform PtrToInt(IntToPtr(x)) to x.
+  bool matchCombineP2IToI2P(MachineInstr &MI, Register &Reg);
+  bool applyCombineP2IToI2P(MachineInstr &MI, Register &Reg);
+
   /// Return true if any explicit use operand on \p MI is defined by a
   /// G_IMPLICIT_DEF.
   bool matchAnyExplicitUseIsUndef(MachineInstr &MI);

diff --git a/llvm/include/llvm/Target/GlobalISel/Combine.td b/llvm/include/llvm/Target/GlobalISel/Combine.td
index 40ed6be..ba19a46 100644 (file)
--- a/llvm/include/llvm/Target/GlobalISel/Combine.td
+++ b/llvm/include/llvm/Target/GlobalISel/Combine.td
@@ -257,6 +257,24 @@ def simplify_add_to_sub: GICombineRule <
   (apply [{ return Helper.applySimplifyAddToSub(*${root}, ${info});}])
 >;
 
+// Fold int2ptr(ptr2int(x)) -> x
+def p2i_to_i2p_matchinfo: GIDefMatchData<"Register">;
+def p2i_to_i2p: GICombineRule<
+  (defs root:$root, p2i_to_i2p_matchinfo:$info),
+  (match (wip_match_opcode G_INTTOPTR):$root,
+    [{ return Helper.matchCombineI2PToP2I(*${root}, ${info}); }]),
+  (apply [{ return Helper.applyCombineI2PToP2I(*${root}, ${info}); }])
+>;
+
+// Fold ptr2int(int2ptr(x)) -> x
+def i2p_to_p2i_matchinfo: GIDefMatchData<"Register">;
+def i2p_to_p2i: GICombineRule<
+  (defs root:$root, i2p_to_p2i_matchinfo:$info),
+  (match (wip_match_opcode G_PTRTOINT):$root,
+    [{ return Helper.matchCombineP2IToI2P(*${root}, ${info}); }]),
+  (apply [{ return Helper.applyCombineP2IToI2P(*${root}, ${info}); }])
+>;
+
 // FIXME: These should use the custom predicate feature once it lands.
 def undef_combines : GICombineGroup<[undef_to_fp_zero, undef_to_int_zero,
                                      undef_to_negative_one,
@@ -267,7 +285,8 @@ def undef_combines : GICombineGroup<[undef_to_fp_zero, undef_to_int_zero,
 
 def identity_combines : GICombineGroup<[select_same_val, right_identity_zero,
                                         binop_same_val, binop_left_to_zero,
-                                        binop_right_to_zero]>;
+                                        binop_right_to_zero, p2i_to_i2p, 
+                                        i2p_to_p2i]>;
 
 def trivial_combines : GICombineGroup<[copy_prop, mul_to_shl]>;
 def all_combines : GICombineGroup<[trivial_combines, ptr_add_immed_chain,

diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index 422b71b..a9ec1d4 100644 (file)
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -1545,6 +1545,39 @@ bool CombinerHelper::tryCombineShiftToUnmerge(MachineInstr &MI,
   return false;
 }
 
+bool CombinerHelper::matchCombineI2PToP2I(MachineInstr &MI, Register &Reg) {
+  assert(MI.getOpcode() == TargetOpcode::G_INTTOPTR && "Expected a G_INTTOPTR");
+  Register DstReg = MI.getOperand(0).getReg();
+  LLT DstTy = MRI.getType(DstReg);
+  Register SrcReg = MI.getOperand(1).getReg();
+  return mi_match(SrcReg, MRI,
+                  m_GPtrToInt(m_all_of(m_SpecificType(DstTy), m_Reg(Reg))));
+}
+
+bool CombinerHelper::applyCombineI2PToP2I(MachineInstr &MI, Register &Reg) {
+  assert(MI.getOpcode() == TargetOpcode::G_INTTOPTR && "Expected a G_INTTOPTR");
+  Register DstReg = MI.getOperand(0).getReg();
+  Builder.setInstr(MI);
+  Builder.buildCopy(DstReg, Reg);
+  MI.eraseFromParent();
+  return true;
+}
+
+bool CombinerHelper::matchCombineP2IToI2P(MachineInstr &MI, Register &Reg) {
+  assert(MI.getOpcode() == TargetOpcode::G_PTRTOINT && "Expected a G_PTRTOINT");
+  Register SrcReg = MI.getOperand(1).getReg();
+  return mi_match(SrcReg, MRI, m_GIntToPtr(m_Reg(Reg)));
+}
+
+bool CombinerHelper::applyCombineP2IToI2P(MachineInstr &MI, Register &Reg) {
+  assert(MI.getOpcode() == TargetOpcode::G_PTRTOINT && "Expected a G_PTRTOINT");
+  Register DstReg = MI.getOperand(0).getReg();
+  Builder.setInstr(MI);
+  Builder.buildZExtOrTrunc(DstReg, Reg);
+  MI.eraseFromParent();
+  return true;
+}
+
 bool CombinerHelper::matchAnyExplicitUseIsUndef(MachineInstr &MI) {
   return any_of(MI.explicit_uses(), [this](const MachineOperand &MO) {
     return MO.isReg() &&

diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/combine-inttoptr-ptrtoint.mir b/llvm/test/CodeGen/AArch64/GlobalISel/combine-inttoptr-ptrtoint.mir
new file mode 100644 (file)
index 0000000..d99b389
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/combine-inttoptr-ptrtoint.mir
@@ -0,0 +1,33 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs -mtriple aarch64-unknown-unknown %s -o - | FileCheck %s
+# RUN: llc -debugify-and-strip-all-safe -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs -mtriple aarch64-unknown-unknown %s -o - | FileCheck %s
+---
+name:            test_combine_inttoptr_same_addressspace
+body:             |
+  bb.1:
+  liveins: $x0, $x1
+
+    ; CHECK-LABEL: name: test_combine_inttoptr_same_addressspace
+    ; CHECK: [[COPY:%[0-9]+]]:_(p64) = COPY $x0
+    ; CHECK: $x1 = COPY [[COPY]](p64)
+    %0:_(p64) = COPY $x0
+    %1:_(s64) = G_PTRTOINT %0
+    %2:_(p64) = G_INTTOPTR %1
+    $x1 = COPY %2
+...
+---
+name:            test_combine_inttoptr_diff_addressspace
+body:             |
+  bb.1:
+  liveins: $x0, $x1
+
+    ; CHECK-LABEL: name: test_combine_inttoptr_diff_addressspace
+    ; CHECK: [[COPY:%[0-9]+]]:_(p0) = COPY $x0
+    ; CHECK: [[PTRTOINT:%[0-9]+]]:_(s64) = G_PTRTOINT [[COPY]](p0)
+    ; CHECK: [[INTTOPTR:%[0-9]+]]:_(p64) = G_INTTOPTR [[PTRTOINT]](s64)
+    ; CHECK: $x1 = COPY [[INTTOPTR]](p64)
+    %0:_(p0) = COPY $x0
+    %1:_(s64) = G_PTRTOINT %0
+    %2:_(p64) = G_INTTOPTR %1
+    $x1 = COPY %2
+...

diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/combine-ptrtoint.mir b/llvm/test/CodeGen/AArch64/GlobalISel/combine-ptrtoint.mir
new file mode 100644 (file)
index 0000000..8164b1b
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/combine-ptrtoint.mir
@@ -0,0 +1,17 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs -mtriple aarch64-unknown-unknown %s -o - | FileCheck %s
+# RUN: llc -debugify-and-strip-all-safe -run-pass=aarch64-prelegalizer-combiner -verify-machineinstrs -mtriple aarch64-unknown-unknown %s -o - | FileCheck %s
+---
+name:            test_combine_ptrtoint
+body:             |
+  bb.1:
+  liveins: $x0, $x1
+
+    ; CHECK-LABEL: name: test_combine_ptrtoint
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+    ; CHECK: $x1 = COPY [[COPY]](s64)
+    %0:_(s64) = COPY $x0
+    %1:_(p64) = G_INTTOPTR %0
+    %2:_(s64) = G_PTRTOINT %1
+    $x1 = COPY %2
+...