[llvm-branch-commits] [llvm-branch] r325501 - Merging r325148:

[Hans Wennborg via llvm-branch-commits]

Author: hans
Date: Mon Feb 19 06:16:41 2018
New Revision: 325501

URL: http://llvm.org/viewvc/llvm-project?rev=325501&view=rev
Log:
Merging r325148:
------------------------------------------------------------------------
r325148 | ctopper | 2018-02-14 19:08:33 +0100 (Wed, 14 Feb 2018) | 7 lines

[InstCombine] Don't fold select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W)) if the binop is rem or div.

The select may have been preventing a division by zero or INT_MIN/-1 so removing it might not be safe.

Fixes PR36362.

Differential Revision: https://reviews.llvm.org/D43276
------------------------------------------------------------------------

Added:
    llvm/branches/release_60/test/Transforms/InstCombine/pr36362.ll
      - copied unchanged from r325148, llvm/trunk/test/Transforms/InstCombine/pr36362.ll
Modified:
    llvm/branches/release_60/   (props changed)
    llvm/branches/release_60/lib/Transforms/InstCombine/InstCombineSelect.cpp

Propchange: llvm/branches/release_60/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Mon Feb 19 06:16:41 2018
@@ -1,3 +1,3 @@
 /llvm/branches/Apple/Pertwee:110850,110961
 /llvm/branches/type-system-rewrite:133420-134817
-/llvm/trunk:155241,321751,321789,321791,321806,321862,321870,321872,321878,321911,321980,321991,321993-321994,322003,322016,322053,322056,322103,322106,322108,322123,322131,322223,322272,322313,322372,322473,322623,322644,322724,322767,322875,322878-322879,322900,322904-322905,322973,322993,323034,323155,323190,323307,323331,323355,323369,323371,323384,323469,323515,323536,323582,323643,323671-323672,323706,323710,323759,323781,323810-323811,323813,323857,323907-323909,323913,323915,324002,324039,324353,324422,324449,324497,324576,324645,324746,324772,324962,325049,325085,325139,325168
+/llvm/trunk:155241,321751,321789,321791,321806,321862,321870,321872,321878,321911,321980,321991,321993-321994,322003,322016,322053,322056,322103,322106,322108,322123,322131,322223,322272,322313,322372,322473,322623,322644,322724,322767,322875,322878-322879,322900,322904-322905,322973,322993,323034,323155,323190,323307,323331,323355,323369,323371,323384,323469,323515,323536,323582,323643,323671-323672,323706,323710,323759,323781,323810-323811,323813,323857,323907-323909,323913,323915,324002,324039,324353,324422,324449,324497,324576,324645,324746,324772,324962,325049,325085,325139,325148,325168

Modified: llvm/branches/release_60/lib/Transforms/InstCombine/InstCombineSelect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_60/lib/Transforms/InstCombine/InstCombineSelect.cpp?rev=325501&r1=325500&r2=325501&view=diff
==============================================================================
--- llvm/branches/release_60/lib/Transforms/InstCombine/InstCombineSelect.cpp (original)
+++ llvm/branches/release_60/lib/Transforms/InstCombine/InstCombineSelect.cpp Mon Feb 19 06:16:41 2018
@@ -1643,11 +1643,25 @@ Instruction *InstCombiner::visitSelectIn
     }
   }
 
+  auto canMergeSelectThroughBinop = [](BinaryOperator *BO) {
+    // The select might be preventing a division by 0.
+    switch (BO->getOpcode()) {
+    default:
+      return true;
+    case Instruction::SRem:
+    case Instruction::URem:
+    case Instruction::SDiv:
+    case Instruction::UDiv:
+      return false;
+    }
+  };
+
   // Try to simplify a binop sandwiched between 2 selects with the same
   // condition.
   // select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z)
   BinaryOperator *TrueBO;
-  if (match(TrueVal, m_OneUse(m_BinOp(TrueBO)))) {
+  if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) &&
+      canMergeSelectThroughBinop(TrueBO)) {
     if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(0))) {
       if (TrueBOSI->getCondition() == CondVal) {
         TrueBO->setOperand(0, TrueBOSI->getTrueValue());
@@ -1666,7 +1680,8 @@ Instruction *InstCombiner::visitSelectIn
 
   // select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W))
   BinaryOperator *FalseBO;
-  if (match(FalseVal, m_OneUse(m_BinOp(FalseBO)))) {
+  if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) &&
+      canMergeSelectThroughBinop(FalseBO)) {
     if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(0))) {
       if (FalseBOSI->getCondition() == CondVal) {
         FalseBO->setOperand(0, FalseBOSI->getFalseValue());