[llvm] d307174 - [ConstantRange] Use APInt::or/APInt::and for single elements.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-04-01T09:50:24+01:00
New Revision: d307174e1d9e66a9e5a1e936ac3736343c3fe381

URL: https://github.com/llvm/llvm-project/commit/d307174e1d9e66a9e5a1e936ac3736343c3fe381
DIFF: https://github.com/llvm/llvm-project/commit/d307174e1d9e66a9e5a1e936ac3736343c3fe381.diff

LOG: [ConstantRange] Use APInt::or/APInt::and for single elements.

Currently ConstantRange::binaryAnd/binaryOr results are too pessimistic
for single element constant ranges.

If both operands are single element ranges, we can use APInt's AND and
OR implementations directly.

Note that some other binary operations on constant ranges can cover the
single element cases naturally, but for OR and AND this unfortunately is
not the case.

Reviewers: nikic, spatel, lebedev.ri

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D76446

Added: 
    

Modified: 
    llvm/lib/IR/ConstantRange.cpp
    llvm/test/Transforms/Attributor/range.ll
    llvm/test/Transforms/CorrelatedValuePropagation/range.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index b8c57533568b..eabaaa203927 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -1196,6 +1196,10 @@ ConstantRange::binaryAnd(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
     return getEmpty();
 
+  // Use APInt's implementation of AND for single element ranges.
+  if (isSingleElement() && Other.isSingleElement())
+    return {*getSingleElement() & *Other.getSingleElement()};
+
   // TODO: replace this with something less conservative
 
   APInt umin = APIntOps::umin(Other.getUnsignedMax(), getUnsignedMax());
@@ -1207,6 +1211,10 @@ ConstantRange::binaryOr(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
     return getEmpty();
 
+  // Use APInt's implementation of OR for single element ranges.
+  if (isSingleElement() && Other.isSingleElement())
+    return {*getSingleElement() | *Other.getSingleElement()};
+
   // TODO: replace this with something less conservative
 
   APInt umax = APIntOps::umax(getUnsignedMin(), Other.getUnsignedMin());

diff  --git a/llvm/test/Transforms/Attributor/range.ll b/llvm/test/Transforms/Attributor/range.ll
index 1e93e97634b2..ef8cd5234326 100644
--- a/llvm/test/Transforms/Attributor/range.ll
+++ b/llvm/test/Transforms/Attributor/range.ll
@@ -1276,13 +1276,11 @@ define i32 @ret1or2(i1 %c) {
 define i1 @callee_range_1(i1 %c1, i1 %c2, i1 %c3) {
 ; OLD_PM-LABEL: define {{[^@]+}}@callee_range_1
 ; OLD_PM-SAME: (i1 [[C1:%.*]], i1 [[C2:%.*]], i1 [[C3:%.*]])
-; OLD_PM-NEXT:    [[F:%.*]] = and i1 true, true
-; OLD_PM-NEXT:    ret i1 [[F]]
+; OLD_PM-NEXT:    ret i1 true
 ;
 ; NEW_PM-LABEL: define {{[^@]+}}@callee_range_1
 ; NEW_PM-SAME: (i1 [[C1:%.*]], i1 [[C2:%.*]], i1 [[C3:%.*]])
-; NEW_PM-NEXT:    [[F:%.*]] = and i1 true, true
-; NEW_PM-NEXT:    ret i1 [[F]]
+; NEW_PM-NEXT:    ret i1 true
 ;
 ; CGSCC_OLD_PM-LABEL: define {{[^@]+}}@callee_range_1
 ; CGSCC_OLD_PM-SAME: (i1 [[C1:%.*]], i1 [[C2:%.*]], i1 [[C3:%.*]])

diff  --git a/llvm/test/Transforms/CorrelatedValuePropagation/range.ll b/llvm/test/Transforms/CorrelatedValuePropagation/range.ll
index 6315e3bd74da..634c37568ea3 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/range.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/range.ll
@@ -457,7 +457,7 @@ define i1 @test14_slt(i32 %a) {
 ; CHECK-NEXT:    br i1 [[CMP]], label [[THEN:%.*]], label [[ELSE:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[RESULT:%.*]] = or i1 false, false
-; CHECK-NEXT:    ret i1 [[RESULT]]
+; CHECK-NEXT:    ret i1 false
 ; CHECK:       else:
 ; CHECK-NEXT:    ret i1 false
 ;
@@ -508,7 +508,7 @@ define i1 @test14_sgt(i32 %a) {
 ; CHECK-NEXT:    br i1 [[CMP]], label [[THEN:%.*]], label [[ELSE:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[RESULT:%.*]] = or i1 false, false
-; CHECK-NEXT:    ret i1 [[RESULT]]
+; CHECK-NEXT:    ret i1 false
 ; CHECK:       else:
 ; CHECK-NEXT:    ret i1 false
 ;
@@ -585,7 +585,7 @@ define i1 @test14_ugt(i32 %a) {
 ; CHECK-NEXT:    br i1 [[CMP]], label [[THEN:%.*]], label [[ELSE:%.*]]
 ; CHECK:       then:
 ; CHECK-NEXT:    [[RESULT:%.*]] = or i1 false, false
-; CHECK-NEXT:    ret i1 [[RESULT]]
+; CHECK-NEXT:    ret i1 false
 ; CHECK:       else:
 ; CHECK-NEXT:    ret i1 false
 ;
@@ -629,6 +629,31 @@ else:
   ret i1 false
 }
 
+define i1 @test14_ugt_and(i32 %a) {
+; CHECK-LABEL: @test14_ugt_and(
+; CHECK-NEXT:    [[A_OFF:%.*]] = add i32 [[A:%.*]], -8
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i32 [[A_OFF]], 8
+; CHECK-NEXT:    br i1 [[CMP]], label [[THEN:%.*]], label [[ELSE:%.*]]
+; CHECK:       then:
+; CHECK-NEXT:    [[RESULT:%.*]] = and i1 false, false
+; CHECK-NEXT:    ret i1 false
+; CHECK:       else:
+; CHECK-NEXT:    ret i1 false
+;
+  %a.off = add i32 %a, -8
+  %cmp = icmp ugt i32 %a.off, 8
+  br i1 %cmp, label %then, label %else
+
+then:
+  %dead.1 = icmp eq i32 %a, 8
+  %dead.2 = icmp eq i32 %a, 16
+  %result = and i1 %dead.1, %dead.2
+  ret i1 %result
+
+else:
+  ret i1 false
+}
+
 @limit = external global i32
 define i1 @test15(i32 %a) {
 ; CHECK-LABEL: @test15(