[llvm] r375396 - [CVP] Deduce no-wrap on `mul`

[Roman Lebedev via llvm-commits]

Author: lebedevri
Date: Mon Oct 21 01:21:44 2019
New Revision: 375396

URL: http://llvm.org/viewvc/llvm-project?rev=375396&view=rev
Log:
[CVP] Deduce no-wrap on `mul`

Summary:
`ConstantRange::makeGuaranteedNoWrapRegion()` knows how to deal with `mul`
since rL335646, there is exhaustive test coverage.
This is already used by CVP's `processOverflowIntrinsic()`,
and by SCEV's `StrengthenNoWrapFlags()`

That being said, currently, this doesn't help much in the end:
| statistic                              |     old |     new | delta | percentage |
| correlated-value-propagation.NumMulNSW |       4 |     275 |   271 |   6775.00% |
| correlated-value-propagation.NumMulNUW |       4 |    1323 |  1319 |  32975.00% |
| correlated-value-propagation.NumMulNW  |       8 |    1598 |  1590 |  19875.00% |
| correlated-value-propagation.NumNSW    |    5715 |    5986 |   271 |      4.74% |
| correlated-value-propagation.NumNUW    |    9193 |   10512 |  1319 |     14.35% |
| correlated-value-propagation.NumNW     |   14908 |   16498 |  1590 |     10.67% |
| instcount.NumAddInst                   |  275871 |  275869 |    -2 |      0.00% |
| instcount.NumBrInst                    |  708234 |  708232 |    -2 |      0.00% |
| instcount.NumMulInst                   |   43812 |   43810 |    -2 |      0.00% |
| instcount.NumPHIInst                   |  316786 |  316784 |    -2 |      0.00% |
| instcount.NumTruncInst                 |   62165 |   62167 |     2 |      0.00% |
| instcount.NumUDivInst                  |    2528 |    2526 |    -2 |     -0.08% |
| instcount.TotalBlocks                  |  842995 |  842993 |    -2 |      0.00% |
| instcount.TotalInsts                   | 7376486 | 7376478 |    -8 |      0.00% |
(^ test-suite plain, tests still pass)

Reviewers: nikic, reames, luqmana, sanjoy, timshen

Reviewed By: reames

Subscribers: hiraditya, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69203

Modified:
    llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
    llvm/trunk/test/Transforms/CorrelatedValuePropagation/mul.ll

Modified: llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp?rev=375396&r1=375395&r2=375396&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp Mon Oct 21 01:21:44 2019
@@ -860,6 +860,7 @@ static bool runImpl(Function &F, LazyVal
         break;
       case Instruction::Add:
       case Instruction::Sub:
+      case Instruction::Mul:
         BBChanged |= processBinOp(cast<BinaryOperator>(II), LVI);
         break;
       case Instruction::And:

Modified: llvm/trunk/test/Transforms/CorrelatedValuePropagation/mul.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CorrelatedValuePropagation/mul.ll?rev=375396&r1=375395&r2=375396&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/CorrelatedValuePropagation/mul.ll (original)
+++ llvm/trunk/test/Transforms/CorrelatedValuePropagation/mul.ll Mon Oct 21 01:21:44 2019
@@ -7,7 +7,7 @@ define i8 @test0(i8 %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i8 [[A:%.*]], 3
 ; CHECK-NEXT:    br i1 [[CMP]], label [[BB:%.*]], label [[EXIT:%.*]]
 ; CHECK:       bb:
-; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[A]], 50
+; CHECK-NEXT:    [[MUL:%.*]] = mul nuw nsw i8 [[A]], 50
 ; CHECK-NEXT:    ret i8 [[MUL]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret i8 0
@@ -30,7 +30,7 @@ define i8 @test1(i8 %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i8 [[A:%.*]], 4
 ; CHECK-NEXT:    br i1 [[CMP]], label [[BB:%.*]], label [[EXIT:%.*]]
 ; CHECK:       bb:
-; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[A]], 50
+; CHECK-NEXT:    [[MUL:%.*]] = mul nuw i8 [[A]], 50
 ; CHECK-NEXT:    ret i8 [[MUL]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret i8 0
@@ -53,7 +53,7 @@ define i8 @test2(i8 %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i8 [[A:%.*]], 6
 ; CHECK-NEXT:    br i1 [[CMP]], label [[BB:%.*]], label [[EXIT:%.*]]
 ; CHECK:       bb:
-; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[A]], 50
+; CHECK-NEXT:    [[MUL:%.*]] = mul nuw i8 [[A]], 50
 ; CHECK-NEXT:    ret i8 [[MUL]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret i8 0
@@ -101,7 +101,7 @@ define i8 @test4(i8 %a) {
 ; CHECK-NEXT:    [[COND:%.*]] = and i1 [[CMP1]], [[CMP2]]
 ; CHECK-NEXT:    br i1 [[COND]], label [[BB:%.*]], label [[EXIT:%.*]]
 ; CHECK:       bb:
-; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[A]], 50
+; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i8 [[A]], 50
 ; CHECK-NEXT:    ret i8 [[MUL]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret i8 0