[PATCH] D88528: [IndVars] Support different types of ExitCount when optimizing exit conds
Max Kazantsev via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 13 03:24:54 PST 2020
mkazantsev updated this revision to Diff 305072.
mkazantsev retitled this revision from "[IndVars] Support different types" to "[IndVars] Support different types of ExitCount when optimizing exit conds".
mkazantsev edited the summary of this revision.
mkazantsev added reviewers: fhahn, skatkov, lebedev.ri, reames.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D88528/new/
https://reviews.llvm.org/D88528
Files:
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
Index: llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
===================================================================
--- llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
+++ llvm/test/Transforms/IndVarSimplify/predicated_ranges.ll
@@ -624,6 +624,7 @@
; CHECK-NEXT: preheader:
; CHECK-NEXT: [[LEN:%.*]] = load i32, i32* [[P:%.*]], align 4
; CHECK-NEXT: [[START:%.*]] = zext i32 [[LEN]] to i64
+; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[LEN]], -1
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[START]], [[PREHEADER:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
@@ -631,9 +632,8 @@
; CHECK-NEXT: br i1 [[ZERO_COND]], label [[EXIT:%.*]], label [[RANGE_CHECK_BLOCK:%.*]]
; CHECK: range_check_block:
; CHECK-NEXT: [[IV_NEXT]] = sub nsw i64 [[IV]], 1
-; CHECK-NEXT: [[NARROW:%.*]] = trunc i64 [[IV_NEXT]] to i32
-; CHECK-NEXT: [[RANGE_CHECK:%.*]] = icmp ult i32 [[NARROW]], [[LEN]]
-; CHECK-NEXT: br i1 [[RANGE_CHECK]], label [[BACKEDGE]], label [[FAIL:%.*]]
+; CHECK-NEXT: [[RANGE_CHECK1:%.*]] = icmp ult i32 [[TMP0]], [[LEN]]
+; CHECK-NEXT: br i1 [[RANGE_CHECK1]], label [[BACKEDGE]], label [[FAIL:%.*]]
; CHECK: backedge:
; CHECK-NEXT: [[EL_PTR:%.*]] = getelementptr i32, i32* [[ARR:%.*]], i64 [[IV]]
; CHECK-NEXT: [[EL:%.*]] = load i32, i32* [[EL_PTR]], align 4
@@ -678,6 +678,7 @@
; CHECK-NEXT: preheader:
; CHECK-NEXT: [[LEN:%.*]] = load i32, i32* [[P:%.*]], align 4
; CHECK-NEXT: [[START:%.*]] = zext i32 [[LEN]] to i64
+; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[LEN]], -1
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[START]], [[PREHEADER:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
@@ -685,9 +686,8 @@
; CHECK-NEXT: br i1 [[ZERO_COND]], label [[EXIT:%.*]], label [[RANGE_CHECK_BLOCK:%.*]]
; CHECK: range_check_block:
; CHECK-NEXT: [[IV_NEXT]] = sub nsw i64 [[IV]], 1
-; CHECK-NEXT: [[NARROW:%.*]] = trunc i64 [[IV_NEXT]] to i32
-; CHECK-NEXT: [[RANGE_CHECK:%.*]] = icmp uge i32 [[NARROW]], [[LEN]]
-; CHECK-NEXT: br i1 [[RANGE_CHECK]], label [[FAIL:%.*]], label [[BACKEDGE]]
+; CHECK-NEXT: [[RANGE_CHECK1:%.*]] = icmp uge i32 [[TMP0]], [[LEN]]
+; CHECK-NEXT: br i1 [[RANGE_CHECK1]], label [[FAIL:%.*]], label [[BACKEDGE]]
; CHECK: backedge:
; CHECK-NEXT: [[EL_PTR:%.*]] = getelementptr i32, i32* [[ARR:%.*]], i64 [[IV]]
; CHECK-NEXT: [[EL:%.*]] = load i32, i32* [[EL_PTR]], align 4
Index: llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -1389,6 +1389,20 @@
const SCEV *LHSS = SE->getSCEVAtScope(LHS, L);
const SCEV *RHSS = SE->getSCEVAtScope(RHS, L);
+ auto *ARTy = LHSS->getType();
+ auto *MaxIterTy = MaxIter->getType();
+ if (ARTy != MaxIterTy) {
+ // If AR's type is wider, just extend the type of max iter.
+ if (SE->getTypeSizeInBits(ARTy) > SE->getTypeSizeInBits(MaxIterTy))
+ MaxIter = SE->getZeroExtendExpr(MaxIter, ARTy);
+ else {
+ const SCEV *MinusOne = SE->getMinusOne(ARTy);
+ auto *MaxAllowedIter = SE->getZeroExtendExpr(MinusOne, MaxIterTy);
+ if (!SE->isKnownPredicateAt(ICmpInst::ICMP_ULE, MaxIter, MaxAllowedIter, BI))
+ return CannotOptimize;
+ MaxIter = SE->getTruncateExpr(MaxIter, ARTy);
+ }
+ }
if (SkipLastIter) {
const SCEV *One = SE->getOne(MaxIter->getType());
MaxIter = SE->getMinusSCEV(MaxIter, One);
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