[llvm] r207338 - DAGCombiner: Simplify code a bit, make more transforms work with vectors.

Patrik Hägglund H patrik.h.hagglund at ericsson.com
Fri May 2 04:48:08 PDT 2014


Hi Benjamin,

This commit is causing a regression for an llvm-stress test, as shown below.

/Patrik Hägglund

bin/llvm-stress -size 185 -seed 7564 | bin/llc -march=x86-64 -mcpu=corei7 -o /dev/null

llc: ../lib/CodeGen/SelectionDAG/SelectionDAG.cpp:5728: void llvm::SelectionDAG::ReplaceAllUsesWith(llvm::SDNode *, llvm::SDNode *): Assertion `(!From->hasAnyUseOfValue(i) || From->getValueType(i) == To->getValueType(i)) && "Cannot use this version of ReplaceAllUsesWith!"' failed.
0  llc             0x00000000010b5a55 llvm::sys::PrintStackTrace(_IO_FILE*) + 37
1  llc             0x00000000010b5e93
2  libpthread.so.0 0x00007f7d65bcb7c0
3  libc.so.6       0x00007f7d64ecfb35 gsignal + 53
4  libc.so.6       0x00007f7d64ed1111 abort + 385
5  libc.so.6       0x00007f7d64ec89f0 __assert_fail + 240
6  llc             0x0000000000f3a524
7  llc             0x0000000000ec4e45 llvm::SelectionDAG::Combine(llvm::CombineLevel, llvm::AliasAnalysis&, llvm::CodeGenOpt::Level) + 1573
8  llc             0x0000000000fad035 llvm::SelectionDAGISel::CodeGenAndEmitDAG() + 901
9  llc             0x0000000000fac368 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) + 6504
10 llc             0x0000000000fa9c64 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) + 1332
11 llc             0x0000000000c3261c llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 124
12 llc             0x0000000000e1f20a llvm::FPPassManager::runOnFunction(llvm::Function&) + 362
13 llc             0x0000000000e1f49b llvm::FPPassManager::runOnModule(llvm::Module&) + 43
14 llc             0x0000000000e1fa37 llvm::legacy::PassManagerImpl::run(llvm::Module&) + 999
15 llc             0x000000000056d835 main + 6549
16 libc.so.6       0x00007f7d64ebbc16 __libc_start_main + 230
17 llc             0x000000000056bdb9
Stack dump:
0.      Program arguments: bin/llc -march=x86-64 -mcpu=corei7 -o /dev/null
1.      Running pass 'Function Pass Manager' on module '<stdin>'.
2.      Running pass 'X86 DAG->DAG Instruction Selection' on function '@autogen_SD7564'
Abort


-----Original Message-----
From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-bounces at cs.uiuc.edu] On Behalf Of Benjamin Kramer
Sent: den 27 april 2014 01:10
To: llvm-commits at cs.uiuc.edu
Subject: [llvm] r207338 - DAGCombiner: Simplify code a bit, make more transforms work with vectors.

Author: d0k
Date: Sat Apr 26 18:09:49 2014
New Revision: 207338

URL: http://llvm.org/viewvc/llvm-project?rev=207338&view=rev
Log:
DAGCombiner: Simplify code a bit, make more transforms work with vectors.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/X86/vector-idiv.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=207338&r1=207337&r2=207338&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sat Apr 26 18:09:49 2014
@@ -644,8 +644,13 @@ static ConstantSDNode *isConstOrConstSpl
   if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N))
     return CN;
 
-  if (BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(N))
-    return BV->getConstantSplatValue();
+  if (BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(N)) {
+    ConstantSDNode *CN = BV->getConstantSplatValue();
+
+    // BuildVectors can truncate their operands. Ignore that case here.
+    if (CN && CN->getValueType(0) == N.getValueType().getScalarType())
+      return CN;
+  }
 
   return nullptr;
 }
@@ -1957,8 +1962,8 @@ SDValue DAGCombiner::visitMUL(SDNode *N)
 SDValue DAGCombiner::visitSDIV(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
-  ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getNode());
-  ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.getNode());
+  ConstantSDNode *N0C = isConstOrConstSplat(N0);
+  ConstantSDNode *N1C = isConstOrConstSplat(N1);
   EVT VT = N->getValueType(0);
 
   // fold vector ops
@@ -1985,25 +1990,15 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
                          N0, N1);
   }
 
-  const APInt *Divisor = nullptr;
-  if (N1C) {
-    Divisor = &N1C->getAPIntValue();
-  } else if (N1.getValueType().isVector() &&
-             N1->getOpcode() == ISD::BUILD_VECTOR) {
-    BuildVectorSDNode *BV = cast<BuildVectorSDNode>(N->getOperand(1));
-    if (ConstantSDNode *C = BV->getConstantSplatValue())
-      Divisor = &C->getAPIntValue();
-  }
-
   // fold (sdiv X, pow2) -> simple ops after legalize
-  if (Divisor && !!*Divisor &&
-      (Divisor->isPowerOf2() || (-*Divisor).isPowerOf2())) {
+  if (N1C && !N1C->isNullValue() && (N1C->getAPIntValue().isPowerOf2() ||
+                                     (-N1C->getAPIntValue()).isPowerOf2())) {
     // If dividing by powers of two is cheap, then don't perform the following
     // fold.
     if (TLI.isPow2DivCheap())
       return SDValue();
 
-    unsigned lg2 = Divisor->countTrailingZeros();
+    unsigned lg2 = N1C->getAPIntValue().countTrailingZeros();
 
     // Splat the sign bit into the register
     SDValue SGN =
@@ -2025,7 +2020,7 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
 
     // If we're dividing by a positive value, we're done.  Otherwise, we must
     // negate the result.
-    if (Divisor->isNonNegative())
+    if (N1C->getAPIntValue().isNonNegative())
       return SRA;
 
     AddToWorkList(SRA.getNode());
@@ -2034,7 +2029,7 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
 
   // if integer divide is expensive and we satisfy the requirements, emit an
   // alternate sequence.
-  if ((N1C || N1->getOpcode() == ISD::BUILD_VECTOR) && !TLI.isIntDivCheap()) {
+  if (N1C && !TLI.isIntDivCheap()) {
     SDValue Op = BuildSDIV(N);
     if (Op.getNode()) return Op;
   }
@@ -2052,8 +2047,8 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
 SDValue DAGCombiner::visitUDIV(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
-  ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getNode());
-  ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.getNode());
+  ConstantSDNode *N0C = isConstOrConstSplat(N0);
+  ConstantSDNode *N1C = isConstOrConstSplat(N1);
   EVT VT = N->getValueType(0);
 
   // fold vector ops
@@ -2086,7 +2081,7 @@ SDValue DAGCombiner::visitUDIV(SDNode *N
     }
   }
   // fold (udiv x, c) -> alternate
-  if ((N1C || N1->getOpcode() == ISD::BUILD_VECTOR) && !TLI.isIntDivCheap()) {
+  if (N1C && !TLI.isIntDivCheap()) {
     SDValue Op = BuildUDIV(N);
     if (Op.getNode()) return Op;
   }
@@ -2104,8 +2099,8 @@ SDValue DAGCombiner::visitUDIV(SDNode *N
 SDValue DAGCombiner::visitSREM(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
-  ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
-  ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
+  ConstantSDNode *N0C = isConstOrConstSplat(N0);
+  ConstantSDNode *N1C = isConstOrConstSplat(N1);
   EVT VT = N->getValueType(0);
 
   // fold (srem c1, c2) -> c1%c2
@@ -2146,8 +2141,8 @@ SDValue DAGCombiner::visitSREM(SDNode *N
 SDValue DAGCombiner::visitUREM(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
-  ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
-  ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
+  ConstantSDNode *N0C = isConstOrConstSplat(N0);
+  ConstantSDNode *N1C = isConstOrConstSplat(N1);
   EVT VT = N->getValueType(0);
 
   // fold (urem c1, c2) -> c1%c2
@@ -11187,28 +11182,20 @@ SDValue DAGCombiner::SimplifySetCC(EVT V
 /// multiplying by a magic number.  See:
 /// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
 SDValue DAGCombiner::BuildSDIV(SDNode *N) {
-  const APInt *Divisor;
-  if (N->getValueType(0).isVector()) {
-    // Handle splat vectors.
-    BuildVectorSDNode *BV = cast<BuildVectorSDNode>(N->getOperand(1));
-    if (ConstantSDNode *C = BV->getConstantSplatValue())
-      Divisor = &C->getAPIntValue();
-    else
-      return SDValue();
-  } else {
-    Divisor = &cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
-  }
+  ConstantSDNode *C = isConstOrConstSplat(N->getOperand(1));
+  if (!C)
+    return SDValue();
 
   // Avoid division by zero.
-  if (!*Divisor)
+  if (!C->getAPIntValue())
     return SDValue();
 
   std::vector<SDNode*> Built;
-  SDValue S = TLI.BuildSDIV(N, *Divisor, DAG, LegalOperations, &Built);
+  SDValue S =
+      TLI.BuildSDIV(N, C->getAPIntValue(), DAG, LegalOperations, &Built);
 
-  for (std::vector<SDNode*>::iterator ii = Built.begin(), ee = Built.end();
-       ii != ee; ++ii)
-    AddToWorkList(*ii);
+  for (SDNode *N : Built)
+    AddToWorkList(N);
   return S;
 }
 
@@ -11217,28 +11204,20 @@ SDValue DAGCombiner::BuildSDIV(SDNode *N
 /// multiplying by a magic number.  See:
 /// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
 SDValue DAGCombiner::BuildUDIV(SDNode *N) {
-  const APInt *Divisor;
-  if (N->getValueType(0).isVector()) {
-    // Handle splat vectors.
-    BuildVectorSDNode *BV = cast<BuildVectorSDNode>(N->getOperand(1));
-    if (ConstantSDNode *C = BV->getConstantSplatValue())
-      Divisor = &C->getAPIntValue();
-    else
-      return SDValue();
-  } else {
-    Divisor = &cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
-  }
+  ConstantSDNode *C = isConstOrConstSplat(N->getOperand(1));
+  if (!C)
+    return SDValue();
 
   // Avoid division by zero.
-  if (!*Divisor)
+  if (!C->getAPIntValue())
     return SDValue();
 
   std::vector<SDNode*> Built;
-  SDValue S = TLI.BuildUDIV(N, *Divisor, DAG, LegalOperations, &Built);
+  SDValue S =
+      TLI.BuildUDIV(N, C->getAPIntValue(), DAG, LegalOperations, &Built);
 
-  for (std::vector<SDNode*>::iterator ii = Built.begin(), ee = Built.end();
-       ii != ee; ++ii)
-    AddToWorkList(*ii);
+  for (SDNode *N : Built)
+    AddToWorkList(N);
   return S;
 }
 

Modified: llvm/trunk/test/CodeGen/X86/vector-idiv.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/vector-idiv.ll?rev=207338&r1=207337&r2=207338&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/vector-idiv.ll (original)
+++ llvm/trunk/test/CodeGen/X86/vector-idiv.ll Sat Apr 26 18:09:49 2014
@@ -151,3 +151,38 @@ define <8 x i32> @test9(<8 x i32> %a) {
 ; AVX: vpsrad $2
 ; AVX: vpadd
 }
+
+define <8 x i32> @test10(<8 x i32> %a) {
+  %rem = urem <8 x i32> %a, <i32 7, i32 7, i32 7, i32 7,i32 7, i32 7, i32 7, i32 7>
+  ret <8 x i32> %rem
+
+; AVX-LABEL: test10:
+; AVX: vpermd
+; AVX: vpmuludq
+; AVX: vshufps	$-35
+; AVX: vpmuludq
+; AVX: vshufps	$-35
+; AVX: vpsubd
+; AVX: vpsrld $1
+; AVX: vpadd
+; AVX: vpsrld $2
+; AVX: vpmulld
+}
+
+define <8 x i32> @test11(<8 x i32> %a) {
+  %rem = srem <8 x i32> %a, <i32 7, i32 7, i32 7, i32 7,i32 7, i32 7, i32 7, i32 7>
+  ret <8 x i32> %rem
+
+; AVX-LABEL: test11:
+; AVX: vpermd
+; AVX: vpmuldq
+; AVX: vshufps	$-35
+; AVX: vpmuldq
+; AVX: vshufps	$-35
+; AVX: vpshufd	$-40
+; AVX: vpadd
+; AVX: vpsrld $31
+; AVX: vpsrad $2
+; AVX: vpadd
+; AVX: vpmulld
+}


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