[llvm] 0607c8d - [PowerPC] Legalize SREM/UREM directly on P9.

[via llvm-commits]

Author: Esme-Yi
Date: 2020-07-06T11:47:31Z
New Revision: 0607c8df7faf71bd726e9d18bafd2f7566984e35

URL: https://github.com/llvm/llvm-project/commit/0607c8df7faf71bd726e9d18bafd2f7566984e35
DIFF: https://github.com/llvm/llvm-project/commit/0607c8df7faf71bd726e9d18bafd2f7566984e35.diff

LOG: [PowerPC] Legalize SREM/UREM directly on P9.

Summary: As Bugzilla-35090 reported, the rationale for using custom lowering SREM/UREM should no longer be true. At the IR level, the div-rem-pairs pass performs the transformation where the remainder is computed from the result of the division when both a required. We should now be able to lower these directly on P9. And the pass also fixed the problem that divide is in a different block than the remainder. This is a patch to remove redundant code and make SREM/UREM legal directly on P9.

Reviewed By: lkail

Differential Revision: https://reviews.llvm.org/D82145

Added: 
    

Modified: 
    llvm/lib/Target/PowerPC/PPCISelLowering.cpp
    llvm/lib/Target/PowerPC/PPCISelLowering.h
    llvm/test/CodeGen/PowerPC/ppc64-P9-mod.ll

Removed: 
    


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diff  --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 532e2659eae1..a31b3fef2aba 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -261,15 +261,16 @@ PPCTargetLowering::PPCTargetLowering(const PPCTargetMachine &TM,
 
   // PowerPC has no SREM/UREM instructions unless we are on P9
   // On P9 we may use a hardware instruction to compute the remainder.
-  // The instructions are not legalized directly because in the cases where the
-  // result of both the remainder and the division is required it is more
-  // efficient to compute the remainder from the result of the division rather
-  // than use the remainder instruction.
+  // When the result of both the remainder and the division is required it is
+  // more efficient to compute the remainder from the result of the division
+  // rather than use the remainder instruction. The instructions are legalized
+  // directly because the DivRemPairsPass performs the transformation at the IR
+  // level.
   if (Subtarget.isISA3_0()) {
-    setOperationAction(ISD::SREM, MVT::i32, Custom);
-    setOperationAction(ISD::UREM, MVT::i32, Custom);
-    setOperationAction(ISD::SREM, MVT::i64, Custom);
-    setOperationAction(ISD::UREM, MVT::i64, Custom);
+    setOperationAction(ISD::SREM, MVT::i32, Legal);
+    setOperationAction(ISD::UREM, MVT::i32, Legal);
+    setOperationAction(ISD::SREM, MVT::i64, Legal);
+    setOperationAction(ISD::UREM, MVT::i64, Legal);
   } else {
     setOperationAction(ISD::SREM, MVT::i32, Expand);
     setOperationAction(ISD::UREM, MVT::i32, Expand);
@@ -10492,18 +10493,6 @@ SDValue PPCTargetLowering::LowerINTRINSIC_VOID(SDValue Op,
   return SDValue();
 }
 
-SDValue PPCTargetLowering::LowerREM(SDValue Op, SelectionDAG &DAG) const {
-  // Check for a DIV with the same operands as this REM.
-  for (auto UI : Op.getOperand(1)->uses()) {
-    if ((Op.getOpcode() == ISD::SREM && UI->getOpcode() == ISD::SDIV) ||
-        (Op.getOpcode() == ISD::UREM && UI->getOpcode() == ISD::UDIV))
-      if (UI->getOperand(0) == Op.getOperand(0) &&
-          UI->getOperand(1) == Op.getOperand(1))
-        return SDValue();
-  }
-  return Op;
-}
-
 // Lower scalar BSWAP64 to xxbrd.
 SDValue PPCTargetLowering::LowerBSWAP(SDValue Op, SelectionDAG &DAG) const {
   SDLoc dl(Op);
@@ -11121,9 +11110,6 @@ SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
 
   case ISD::INTRINSIC_VOID:
     return LowerINTRINSIC_VOID(Op, DAG);
-  case ISD::SREM:
-  case ISD::UREM:
-    return LowerREM(Op, DAG);
   case ISD::BSWAP:
     return LowerBSWAP(Op, DAG);
   case ISD::ATOMIC_CMP_SWAP:

diff  --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index b3f309693e16..98256ae0c359 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -1119,7 +1119,6 @@ namespace llvm {
     SDValue LowerEXTRACT_VECTOR_ELT(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerINTRINSIC_WO_CHAIN(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerINTRINSIC_VOID(SDValue Op, SelectionDAG &DAG) const;
-    SDValue LowerREM(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerBSWAP(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerATOMIC_CMP_SWAP(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSCALAR_TO_VECTOR(SDValue Op, SelectionDAG &DAG) const;

diff  --git a/llvm/test/CodeGen/PowerPC/ppc64-P9-mod.ll b/llvm/test/CodeGen/PowerPC/ppc64-P9-mod.ll
index e3dcf8e5491e..e99074e7f90f 100644
--- a/llvm/test/CodeGen/PowerPC/ppc64-P9-mod.ll
+++ b/llvm/test/CodeGen/PowerPC/ppc64-P9-mod.ll
@@ -88,13 +88,16 @@ entry:
   store i32 %div, i32* @div_resultsw, align 4
   ret void
 ; CHECK-LABEL: modulo_div_sw
-; CHECK-NOT: modsw
-; CHECK: div
-; CHECK-NOT: modsw
-; CHECK: mull
-; CHECK-NOT: modsw
-; CHECK: sub
+; CHECK: modsw {{[0-9]+}}, 3, 4
 ; CHECK: blr
+; CHECK-DRP-LABEL: modulo_div_sw
+; CHECK-DRP-NOT: modsw
+; CHECK-DRP: div
+; CHECK-DRP-NOT: modsw
+; CHECK-DRP: mull
+; CHECK-DRP-NOT: modsw
+; CHECK-DRP: sub
+; CHECK-DRP: blr
 ; CHECK-PWR8-LABEL: modulo_div_sw
 ; CHECK-PWR8: div
 ; CHECK-PWR8: mull
@@ -129,13 +132,16 @@ entry:
   store i32 %div, i32* @div_resultuw, align 4
   ret void
 ; CHECK-LABEL: modulo_div_uw
-; CHECK-NOT: modsw
-; CHECK: div
-; CHECK-NOT: modsw
-; CHECK: mull
-; CHECK-NOT: modsw
-; CHECK: sub
+; CHECK: moduw {{[0-9]+}}, 3, 4
 ; CHECK: blr
+; CHECK-DRP-LABEL: modulo_div_uw
+; CHECK-DRP-NOT: moduw
+; CHECK-DRP: div
+; CHECK-DRP-NOT: moduw
+; CHECK-DRP: mull
+; CHECK-DRP-NOT: moduw
+; CHECK-DRP: sub
+; CHECK-DRP: blr
 ; CHECK-PWR8-LABEL: modulo_div_uw
 ; CHECK-PWR8: div
 ; CHECK-PWR8: mull