[llvm] f1a9a83 - [SCEV] Be robust against IR generated by simple-loop-unswitch
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 21 09:53:57 PST 2019
Author: Philip Reames
Date: 2019-11-21T09:53:43-08:00
New Revision: f1a9a83232230e1c848a91270ebe0d4089f0a803
URL: https://github.com/llvm/llvm-project/commit/f1a9a83232230e1c848a91270ebe0d4089f0a803
DIFF: https://github.com/llvm/llvm-project/commit/f1a9a83232230e1c848a91270ebe0d4089f0a803.diff
LOG: [SCEV] Be robust against IR generated by simple-loop-unswitch
Simple loop unswitch likes to leave around unsimplified and/or/xors. SCEV today bails out on these idioms which is unfortunate in general, and specifically for the unswitch interaction.
Differential Revision: https://reviews.llvm.org/D70459
Added:
Modified:
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 4cde0171f62c..79b35b8c9d21 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -7246,6 +7246,11 @@ ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
ExitLimit EL1 = computeExitLimitFromCondCached(
Cache, L, BO->getOperand(1), ExitIfTrue,
ControlsExit && !EitherMayExit, AllowPredicates);
+ // Be robust against unsimplified IR for the form "and i1 X, true"
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
+ return CI->isOne() ? EL0 : EL1;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0)))
+ return CI->isOne() ? EL1 : EL0;
const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
if (EitherMayExit) {
@@ -7294,6 +7299,11 @@ ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
ExitLimit EL1 = computeExitLimitFromCondCached(
Cache, L, BO->getOperand(1), ExitIfTrue,
ControlsExit && !EitherMayExit, AllowPredicates);
+ // Be robust against unsimplified IR for the form "or i1 X, true"
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1)))
+ return CI->isZero() ? EL0 : EL1;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(0)))
+ return CI->isZero() ? EL1 : EL0;
const SCEV *BECount = getCouldNotCompute();
const SCEV *MaxBECount = getCouldNotCompute();
if (EitherMayExit) {
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
index 36a51c5517fb..30e54f6cdb77 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count-andor.ll
@@ -8,15 +8,17 @@ define void @unsimplified_and1(i32 %n) {
; CHECK-LABEL: 'unsimplified_and1'
; CHECK-NEXT: Classifying expressions for: @unsimplified_and1
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %and = and i1 %becond, true
; CHECK-NEXT: --> %becond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and1
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -36,15 +38,17 @@ define void @unsimplified_and2(i32 %n) {
; CHECK-LABEL: 'unsimplified_and2'
; CHECK-NEXT: Classifying expressions for: @unsimplified_and2
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %and = and i1 true, %becond
; CHECK-NEXT: --> %and U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and2
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -70,9 +74,9 @@ define void @unsimplified_and3(i32 %n) {
; CHECK-NEXT: %and = and i1 false, %becond
; CHECK-NEXT: --> %and U: [0,-1) S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and3
-; CHECK-NEXT: Loop %loop: backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: max backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is 0
+; CHECK-NEXT: Loop %loop: backedge-taken count is false
+; CHECK-NEXT: Loop %loop: max backedge-taken count is false
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is false
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
;
@@ -100,9 +104,9 @@ define void @unsimplified_and4(i32 %n) {
; CHECK-NEXT: %and = and i1 %becond, false
; CHECK-NEXT: --> false U: [0,-1) S: [0,-1) Exits: false LoopDispositions: { %loop: Invariant }
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_and4
-; CHECK-NEXT: Loop %loop: backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: max backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is 0
+; CHECK-NEXT: Loop %loop: backedge-taken count is false
+; CHECK-NEXT: Loop %loop: max backedge-taken count is false
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is false
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
;
@@ -180,15 +184,17 @@ define void @unsimplified_or3(i32 %n) {
; CHECK-LABEL: 'unsimplified_or3'
; CHECK-NEXT: Classifying expressions for: @unsimplified_or3
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %or = or i1 false, %becond
; CHECK-NEXT: --> %or U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_or3
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -208,15 +214,17 @@ define void @unsimplified_or4(i32 %n) {
; CHECK-LABEL: 'unsimplified_or4'
; CHECK-NEXT: Classifying expressions for: @unsimplified_or4
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %or = or i1 %becond, false
; CHECK-NEXT: --> %becond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @unsimplified_or4
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -236,15 +244,17 @@ define void @reversed_and1(i32 %n) {
; CHECK-LABEL: 'reversed_and1'
; CHECK-NEXT: Classifying expressions for: @reversed_and1
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %and = and i1 %becond, true
; CHECK-NEXT: --> %becond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @reversed_and1
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -264,15 +274,17 @@ define void @reversed_and2(i32 %n) {
; CHECK-LABEL: 'reversed_and2'
; CHECK-NEXT: Classifying expressions for: @reversed_and2
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %and = and i1 true, %becond
; CHECK-NEXT: --> %and U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @reversed_and2
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
+; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -354,9 +366,9 @@ define void @reversed_or1(i32 %n) {
; CHECK-NEXT: %or = or i1 %becond, true
; CHECK-NEXT: --> %or U: [-1,0) S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @reversed_or1
-; CHECK-NEXT: Loop %loop: backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: max backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is 0
+; CHECK-NEXT: Loop %loop: backedge-taken count is false
+; CHECK-NEXT: Loop %loop: max backedge-taken count is false
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is false
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
;
@@ -384,9 +396,9 @@ define void @reversed_or2(i32 %n) {
; CHECK-NEXT: %or = or i1 true, %becond
; CHECK-NEXT: --> %or U: [-1,0) S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @reversed_or2
-; CHECK-NEXT: Loop %loop: backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: max backedge-taken count is 0
-; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is 0
+; CHECK-NEXT: Loop %loop: backedge-taken count is false
+; CHECK-NEXT: Loop %loop: max backedge-taken count is false
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is false
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
;
@@ -408,15 +420,17 @@ define void @reversed_or3(i32 %n) {
; CHECK-LABEL: 'reversed_or3'
; CHECK-NEXT: Classifying expressions for: @reversed_or3
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %or = or i1 false, %becond
; CHECK-NEXT: --> %or U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @reversed_or3
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
@@ -436,15 +450,17 @@ define void @reversed_or4(i32 %n) {
; CHECK-LABEL: 'reversed_or4'
; CHECK-NEXT: Classifying expressions for: @reversed_or4
; CHECK-NEXT: %iv = phi i32 [ 0, %entry ], [ %iv.inc, %loop ]
-; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648) Exits: %n LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.inc = add nsw i32 %iv, 1
-; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<nuw><%loop> U: [1,0) S: [1,0) Exits: (1 + %n) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %or = or i1 %becond, false
; CHECK-NEXT: --> %becond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @reversed_or4
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is %n
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is %n
+; CHECK-NEXT: Predicates:
+; CHECK: Loop %loop: Trip multiple is 1
;
entry:
br label %loop
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