[llvm] 07de5d1 - [SCEV] Remember blocks for which we know symbolic exit count but not exact
Max Kazantsev via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 7 02:51:39 PST 2022
Author: Max Kazantsev
Date: 2022-12-07T17:51:30+07:00
New Revision: 07de5d18c90182f5d38fd9b9b3911375d045ff2a
URL: https://github.com/llvm/llvm-project/commit/07de5d18c90182f5d38fd9b9b3911375d045ff2a
DIFF: https://github.com/llvm/llvm-project/commit/07de5d18c90182f5d38fd9b9b3911375d045ff2a.diff
LOG: [SCEV] Remember blocks for which we know symbolic exit count but not exact
The old code didn't bother to memoize blocks for which exact exit count is not
known. As result, in situation when exact isn't known but symbolic is known, this
info was lost. This patch fixes the situation: now we memoize when symbolic is
known (exact always implies symbolic, so this is a strict superset of what was before).
Differential Revision: https://reviews.llvm.org/D139515
Reviewed By: nikic
Added:
Modified:
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/test/Analysis/ScalarEvolution/addrec-computed-during-addrec-calculation.ll
llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
llvm/test/Analysis/ScalarEvolution/trip-count10.ll
llvm/test/Analysis/ScalarEvolution/trip-count7.ll
llvm/test/Analysis/ScalarEvolution/widenable-condition.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 76f0fccab5d0e..53601a8f3e90f 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -8714,8 +8714,13 @@ ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
// We couldn't compute an exact value for this exit, so
// we won't be able to compute an exact value for the loop.
CouldComputeBECount = false;
- else
+ // Remember exit count if either exact or symbolic is known. Because
+ // Exact always implies symbolic, only check symbolic.
+ if (EL.SymbolicMaxNotTaken != getCouldNotCompute())
ExitCounts.emplace_back(ExitBB, EL);
+ else
+ assert(EL.ExactNotTaken == getCouldNotCompute() &&
+ "Exact is known but symbolic isn't?");
// 2. Derive the loop's MaxBECount from each exit's max number of
// non-exiting iterations. Partition the loop exits into two kinds:
diff --git a/llvm/test/Analysis/ScalarEvolution/addrec-computed-during-addrec-calculation.ll b/llvm/test/Analysis/ScalarEvolution/addrec-computed-during-addrec-calculation.ll
index 798cc3546d1bf..fef5db9dcedc6 100644
--- a/llvm/test/Analysis/ScalarEvolution/addrec-computed-during-addrec-calculation.ll
+++ b/llvm/test/Analysis/ScalarEvolution/addrec-computed-during-addrec-calculation.ll
@@ -28,7 +28,7 @@ define void @test(i32* %p) {
; CHECK-NEXT: Determining loop execution counts for: @test
; CHECK-NEXT: Loop %loop2: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop2: constant max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop2: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop2: symbolic max backedge-taken count is -1
; CHECK-NEXT: Loop %loop2: Unpredictable predicated backedge-taken count.
; CHECK-NEXT: Loop %loop3: backedge-taken count is false
; CHECK-NEXT: Loop %loop3: constant max backedge-taken count is false
diff --git a/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll b/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
index d1a896f86ca17..a1c83b4d1744d 100644
--- a/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
+++ b/llvm/test/Analysis/ScalarEvolution/symbolic_max_exit_count.ll
@@ -80,8 +80,8 @@ define i32 @test_litter_conditions(i32 %start, i32 %len) {
; CHECK-NEXT: exit count for range_check_block: ***COULDNOTCOMPUTE***
; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
-; CHECK-NEXT: symbolic max exit count for loop: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is -1
+; CHECK-NEXT: symbolic max exit count for loop: -1
; CHECK-NEXT: symbolic max exit count for range_check_block: ***COULDNOTCOMPUTE***
; CHECK-NEXT: symbolic max exit count for backedge: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
@@ -144,8 +144,8 @@ define i32 @test_litter_conditions_bad_context(i32 %start, i32 %len) {
; CHECK-NEXT: exit count for range_check_block: ***COULDNOTCOMPUTE***
; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
-; CHECK-NEXT: symbolic max exit count for loop: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is -1
+; CHECK-NEXT: symbolic max exit count for loop: -1
; CHECK-NEXT: symbolic max exit count for range_check_block: ***COULDNOTCOMPUTE***
; CHECK-NEXT: symbolic max exit count for backedge: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
@@ -201,8 +201,8 @@ define i32 @test_and_conditions(i32 %start, i32 %len) {
; CHECK-NEXT: exit count for loop: ***COULDNOTCOMPUTE***
; CHECK-NEXT: exit count for backedge: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
-; CHECK-NEXT: symbolic max exit count for loop: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is -1
+; CHECK-NEXT: symbolic max exit count for loop: -1
; CHECK-NEXT: symbolic max exit count for backedge: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
;
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count10.ll b/llvm/test/Analysis/ScalarEvolution/trip-count10.ll
index 825455c4b2a05..fc486a33702db 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count10.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count10.ll
@@ -159,7 +159,7 @@ define void @exit_orcond_nsw(i32 *%a) nounwind {
; CHECK-NEXT: Determining loop execution counts for: @exit_orcond_nsw
; CHECK-NEXT: Loop %for.body.i: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body.i: constant max backedge-taken count is 1
-; CHECK-NEXT: Loop %for.body.i: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %for.body.i: symbolic max backedge-taken count is 1
; CHECK-NEXT: Loop %for.body.i: Unpredictable predicated backedge-taken count.
;
entry:
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count7.ll b/llvm/test/Analysis/ScalarEvolution/trip-count7.ll
index 054a7ce912722..498b5b6b63e4f 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count7.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count7.ll
@@ -65,7 +65,7 @@ define void @Doit_bb7_2E_i([9 x i32]* %x1, [15 x i32]* %c, [17 x i32]* %b, [9 x
; CHECK-NEXT: Determining loop execution counts for: @Doit_bb7_2E_i
; CHECK-NEXT: Loop %bb7.i: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %bb7.i: constant max backedge-taken count is 8
-; CHECK-NEXT: Loop %bb7.i: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %bb7.i: symbolic max backedge-taken count is 8
; CHECK-NEXT: Loop %bb7.i: Unpredictable predicated backedge-taken count.
;
newFuncRoot:
diff --git a/llvm/test/Analysis/ScalarEvolution/widenable-condition.ll b/llvm/test/Analysis/ScalarEvolution/widenable-condition.ll
index 71c87b49465d3..133afa4939f36 100644
--- a/llvm/test/Analysis/ScalarEvolution/widenable-condition.ll
+++ b/llvm/test/Analysis/ScalarEvolution/widenable-condition.ll
@@ -24,7 +24,7 @@ define i32 @wc_max() {
; CHECK-NEXT: Determining loop execution counts for: @wc_max
; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is 1999
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is 1999
; CHECK-NEXT: Loop %loop: Unpredictable predicated backedge-taken count.
;
entry:
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