[TwoAddressInstructionPass] Improve tryInstructionCommute of X86 FMA and vpternlog...

These instructions have 3 operands that can be commuted. The first commute we find may not be the best. So we should keep searching if we performed an aggressive commute. There may still be an operand that is killed or a physical register constraint that might be better.

Differential Revision: https://reviews.llvm.org/D44324

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327188 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 774b76f..539f848 100644 (file)
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1205,6 +1205,7 @@ bool TwoAddressInstructionPass::tryInstructionCommute(MachineInstr *MI,
   if (!MI->isCommutable())
     return false;
 
+  bool MadeChange = false;
   unsigned DstOpReg = MI->getOperand(DstOpIdx).getReg();
   unsigned BaseOpReg = MI->getOperand(BaseOpIdx).getReg();
   unsigned OpsNum = MI->getDesc().getNumOperands();
@@ -1223,8 +1224,8 @@ bool TwoAddressInstructionPass::tryInstructionCommute(MachineInstr *MI,
 
     // If OtherOp dies but BaseOp does not, swap the OtherOp and BaseOp
     // operands. This makes the live ranges of DstOp and OtherOp joinable.
-    bool DoCommute =
-        !BaseOpKilled && isKilled(*MI, OtherOpReg, MRI, TII, LIS, false);
+    bool OtherOpKilled = isKilled(*MI, OtherOpReg, MRI, TII, LIS, false);
+    bool DoCommute = !BaseOpKilled && OtherOpKilled;
 
     if (!DoCommute &&
         isProfitableToCommute(DstOpReg, BaseOpReg, OtherOpReg, MI, Dist)) {
@@ -1235,13 +1236,21 @@ bool TwoAddressInstructionPass::tryInstructionCommute(MachineInstr *MI,
     // If it's profitable to commute, try to do so.
     if (DoCommute && commuteInstruction(MI, DstOpIdx, BaseOpIdx, OtherOpIdx,
                                         Dist)) {
+      MadeChange = true;
       ++NumCommuted;
-      if (AggressiveCommute)
+      if (AggressiveCommute) {
         ++NumAggrCommuted;
-      return true;
+        // There might be more than two commutable operands, update BaseOp and
+        // continue scanning.
+        BaseOpReg = OtherOpReg;
+        BaseOpKilled = OtherOpKilled;
+        continue;
+      }
+      // If this was a commute based on kill, we won't do better continuing.
+      return MadeChange;
     }
   }
-  return false;
+  return MadeChange;
 }
 
 /// For the case where an instruction has a single pair of tied register

diff --git a/test/CodeGen/X86/avx512-vpternlog-commute.ll b/test/CodeGen/X86/avx512-vpternlog-commute.ll
index d812fac..7f3cde0 100644 (file)
--- a/test/CodeGen/X86/avx512-vpternlog-commute.ll
+++ b/test/CodeGen/X86/avx512-vpternlog-commute.ll
@@ -27,8 +27,7 @@ define <16 x i32> @vpternlog_v16i32_102(<16 x i32> %x0, <16 x i32> %x1, <16 x i3
 define <16 x i32> @vpternlog_v16i32_210(<16 x i32> %x0, <16 x i32> %x1, <16 x i32> %x2) {
 ; CHECK-LABEL: vpternlog_v16i32_210:
 ; CHECK:       ## %bb.0:
-; CHECK-NEXT:    vpternlogd $78, %zmm0, %zmm2, %zmm1
-; CHECK-NEXT:    vmovdqa64 %zmm1, %zmm0
+; CHECK-NEXT:    vpternlogd $92, %zmm1, %zmm2, %zmm0
 ; CHECK-NEXT:    retq
   %res = call <16 x i32> @llvm.x86.avx512.mask.pternlog.d.512(<16 x i32> %x2, <16 x i32> %x1, <16 x i32> %x0, i32 114, i16 -1)
   ret <16 x i32> %res
@@ -434,8 +433,7 @@ define <16 x i32> @vpternlog_v16i32_210_maskz(<16 x i32> %x0, <16 x i32> %x1, <1
 ; CHECK-LABEL: vpternlog_v16i32_210_maskz:
 ; CHECK:       ## %bb.0:
 ; CHECK-NEXT:    kmovd %edi, %k1
-; CHECK-NEXT:    vpternlogd $78, %zmm0, %zmm2, %zmm1 {%k1} {z}
-; CHECK-NEXT:    vmovdqa64 %zmm1, %zmm0
+; CHECK-NEXT:    vpternlogd $92, %zmm1, %zmm2, %zmm0 {%k1} {z}
 ; CHECK-NEXT:    retq
   %res = call <16 x i32> @llvm.x86.avx512.maskz.pternlog.d.512(<16 x i32> %x2, <16 x i32> %x1, <16 x i32> %x0, i32 114, i16 %mask)
   ret <16 x i32> %res