[polly] r270408 - [FIX] Synthezise Sdiv/Srem/Udiv instructions correctly.

Johannes Doerfert via llvm-commits llvm-commits at lists.llvm.org
Mon May 23 01:55:48 PDT 2016


Author: jdoerfert
Date: Mon May 23 03:55:43 2016
New Revision: 270408

URL: http://llvm.org/viewvc/llvm-project?rev=270408&view=rev
Log:
[FIX] Synthezise Sdiv/Srem/Udiv instructions correctly.

  This patch simplifies the Sdiv/Srem/Udiv expansion and thereby
  prevents errors, e.g., regarding the insertion point.


Added:
    polly/trunk/test/Isl/CodeGen/udiv_expansion_position.ll
Modified:
    polly/trunk/lib/Support/ScopHelper.cpp
    polly/trunk/test/Isl/CodeGen/param_div_div_div_2.ll

Modified: polly/trunk/lib/Support/ScopHelper.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Support/ScopHelper.cpp?rev=270408&r1=270407&r2=270408&view=diff
==============================================================================
--- polly/trunk/lib/Support/ScopHelper.cpp (original)
+++ polly/trunk/lib/Support/ScopHelper.cpp Mon May 23 03:55:43 2016
@@ -246,15 +246,6 @@ private:
   const Region &R;
   ValueMapT *VMap;
 
-  /// @brief Return the Value for @p E if it is not zero or else the value 1.
-  Value *selectOneIfZero(const SCEV *E, Instruction *IP) {
-    auto *Ty = E->getType();
-    auto *RHS = Expander.expandCodeFor(E, Ty, IP);
-    auto *Zero = ConstantInt::get(Ty, 0);
-    auto *Cond = new ICmpInst(IP, ICmpInst::ICMP_NE, RHS, Zero);
-    return SelectInst::Create(Cond, RHS, ConstantInt::get(Ty, 1), "", IP);
-  }
-
   const SCEV *visitUnknown(const SCEVUnknown *E) {
 
     // If a value mapping was given try if the underlying value is remapped.
@@ -278,15 +269,14 @@ private:
 
     Instruction *StartIP = R.getEnteringBlock()->getTerminator();
 
-    const SCEV *LHSScev = visit(SE.getSCEV(Inst->getOperand(0)));
-    const SCEV *RHSScev = visit(SE.getSCEV(Inst->getOperand(1)));
+    const SCEV *LHSScev = SE.getSCEV(Inst->getOperand(0));
+    const SCEV *RHSScev = SE.getSCEV(Inst->getOperand(1));
+
+    if (!SE.isKnownNonZero(RHSScev))
+      RHSScev = SE.getUMaxExpr(RHSScev, SE.getConstant(E->getType(), 1));
 
-    Value *LHS = Expander.expandCodeFor(LHSScev, E->getType(), StartIP);
-    Value *RHS = nullptr;
-    if (SE.isKnownNonZero(RHSScev))
-      RHS = Expander.expandCodeFor(RHSScev, E->getType(), StartIP);
-    else
-      RHS = selectOneIfZero(RHSScev, StartIP);
+    Value *LHS = expandCodeFor(LHSScev, E->getType(), StartIP);
+    Value *RHS = expandCodeFor(RHSScev, E->getType(), StartIP);
 
     Inst = BinaryOperator::Create((Instruction::BinaryOps)Inst->getOpcode(),
                                   LHS, RHS, Inst->getName() + Name, StartIP);
@@ -308,12 +298,10 @@ private:
     return SE.getSignExtendExpr(visit(E->getOperand()), E->getType());
   }
   const SCEV *visitUDivExpr(const SCEVUDivExpr *E) {
-    if (SE.isKnownNonZero(E->getRHS()))
-      return SE.getUDivExpr(visit(E->getLHS()), visit(E->getRHS()));
     auto *RHSScev = visit(E->getRHS());
-    auto *IP = R.getEnteringBlock()->getTerminator();
-    auto *RHS = selectOneIfZero(RHSScev, IP);
-    return SE.getUDivExpr(visit(E->getLHS()), SE.getSCEV(RHS));
+    if (!SE.isKnownNonZero(E->getRHS()))
+      RHSScev = SE.getUMaxExpr(RHSScev, SE.getConstant(E->getType(), 1));
+    return SE.getUDivExpr(visit(E->getLHS()), RHSScev);
   }
   const SCEV *visitAddExpr(const SCEVAddExpr *E) {
     SmallVector<const SCEV *, 4> NewOps;

Modified: polly/trunk/test/Isl/CodeGen/param_div_div_div_2.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/param_div_div_div_2.ll?rev=270408&r1=270407&r2=270408&view=diff
==============================================================================
--- polly/trunk/test/Isl/CodeGen/param_div_div_div_2.ll (original)
+++ polly/trunk/test/Isl/CodeGen/param_div_div_div_2.ll Mon May 23 03:55:43 2016
@@ -13,15 +13,15 @@
 ;        A[i] += A[(a / b) / (c / d)];
 ;    }
 ;
-; IR:       %[[R0:[0-9]*]] = icmp ne i32 %d, 0
-; IR-NEXT:  %[[R1:[0-9]*]] = select i1 %[[R0]], i32 %d, i32 1
-; IR-NEXT:  %[[R2:[0-9]*]] = udiv i32 %c, %[[R1]]
-; IR-NEXT:  %[[R3:[0-9]*]] = icmp ne i32 %2, 0
-; IR-NEXT:  %[[R4:[0-9]*]] = select i1 %[[R3]], i32 %[[R2]], i32 1
-; IR-NEXT:  %[[R5:[0-9]*]] = icmp ne i32 %b, 0
-; IR-NEXT:  %[[R6:[0-9]*]] = select i1 %[[R5]], i32 %b, i32 1
-; IR-NEXT:  %[[R7:[0-9]*]] = udiv i32 %a, %[[R6]]
-; IR-NEXT:  %[[R8:[0-9]*]] = udiv i32 %[[R7]], %[[R4]]
+; IR:       %[[R0:[.a-zA-Z0-9]*]] = icmp ugt i32 %b, 1
+; IR-NEXT:  %[[R1:[.a-zA-Z0-9]*]] = select i1 %[[R0]], i32 %b, i32 1
+; IR-NEXT:  %[[R2:[.a-zA-Z0-9]*]] = udiv i32 %a, %[[R1]]
+; IR-NEXT:  %[[R5:[.a-zA-Z0-9]*]] = icmp ugt i32 %d, 1
+; IR-NEXT:  %[[R6:[.a-zA-Z0-9]*]] = select i1 %[[R5]], i32 %d, i32 1
+; IR-NEXT:  %[[R7:[.a-zA-Z0-9]*]] = udiv i32 %c, %[[R6]]
+; IR-NEXT:  %[[R3:[.a-zA-Z0-9]*]] = icmp ugt i32 %[[R7]], 1
+; IR-NEXT:  %[[R4:[.a-zA-Z0-9]*]] = select i1 %[[R3]], i32 %[[R7]], i32 1
+; IR-NEXT:  %[[R8:[.a-zA-Z0-9]*]] = udiv i32 %[[R2]], %[[R4]]
 ;
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 

Added: polly/trunk/test/Isl/CodeGen/udiv_expansion_position.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/udiv_expansion_position.ll?rev=270408&view=auto
==============================================================================
--- polly/trunk/test/Isl/CodeGen/udiv_expansion_position.ll (added)
+++ polly/trunk/test/Isl/CodeGen/udiv_expansion_position.ll Mon May 23 03:55:43 2016
@@ -0,0 +1,58 @@
+; RUN: opt %loadPolly -polly-codegen -S < %s | FileCheck %s
+;
+; Verify we do not crash when we synthezise code for the udiv in the SCoP.
+;
+; CHECK: polly.start
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Function Attrs: nounwind uwtable
+define void @RestartModel() #0 {
+entry:
+  br label %for.cond32.preheader
+
+for.cond32.preheader:                             ; preds = %entry, %for.body50.7
+  %i.13 = phi i32 [ 0, %entry ], [ %inc60, %for.body50.7 ]
+  %add = add i32 %i.13, 2
+  %div44 = udiv i32 undef, %add
+  %sub45 = sub i32 16384, %div44
+  %conv46 = trunc i32 %sub45 to i16
+  br label %for.body35
+
+for.body35:                                       ; preds = %for.cond32.preheader
+  br label %for.body50
+
+for.body50:                                       ; preds = %for.body35
+  br label %for.body50.1
+
+for.cond62:                                       ; preds = %for.body50.7
+  %conv46.lcssa = phi i16 [ %conv46, %for.body50.7 ]
+  store i16 %conv46.lcssa, i16* undef, align 2
+  br label %for.end83
+
+for.end83:                                        ; preds = %for.cond62
+  ret void
+
+for.body50.1:                                     ; preds = %for.body50
+  br label %for.body50.2
+
+for.body50.2:                                     ; preds = %for.body50.1
+  br label %for.body50.3
+
+for.body50.3:                                     ; preds = %for.body50.2
+  br label %for.body50.4
+
+for.body50.4:                                     ; preds = %for.body50.3
+  br label %for.body50.5
+
+for.body50.5:                                     ; preds = %for.body50.4
+  br label %for.body50.6
+
+for.body50.6:                                     ; preds = %for.body50.5
+  br label %for.body50.7
+
+for.body50.7:                                     ; preds = %for.body50.6
+  %inc60 = add i32 %i.13, 1
+  %cmp29 = icmp ult i32 %inc60, 128
+  br i1 %cmp29, label %for.cond32.preheader, label %for.cond62
+}




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