[llvm] 5387a38 - [SimpleLoopUnswitch] Freeze individual OR/AND operands.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Sun May 1 12:11:26 PDT 2022
Author: Florian Hahn
Date: 2022-05-01T20:11:05+01:00
New Revision: 5387a38c3891730b943a35d9d3e4b2d9e716acda
URL: https://github.com/llvm/llvm-project/commit/5387a38c3891730b943a35d9d3e4b2d9e716acda
DIFF: https://github.com/llvm/llvm-project/commit/5387a38c3891730b943a35d9d3e4b2d9e716acda.diff
LOG: [SimpleLoopUnswitch] Freeze individual OR/AND operands.
In some cases, it is not enough to freeze the final AND/OR operation
when chaining a number of invariant conditions together.
After creating a chain of ANDs/ORs, we assume all unswitched operands to
be either true or false. But if any of the operands is poison, the rest
of the operands could have any value after branching on the frozen
condition.
To avoid that, freeze individual operands, if needed. In some cases this
may lead to unnecessary freezes, but it seems required at least for some
cases (see trivial-unswitch-freeze-individual-conditions.ll)
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D124554
Added:
Modified:
llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-freeze-individual-conditions.ll
llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-logical-and-or.ll
llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
index b3f12298e92f3..14c1fed9d2020 100644
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -204,13 +204,19 @@ static bool areLoopExitPHIsLoopInvariant(Loop &L, BasicBlock &ExitingBB,
/// branch on a single value.
static void buildPartialUnswitchConditionalBranch(
BasicBlock &BB, ArrayRef<Value *> Invariants, bool Direction,
- BasicBlock &UnswitchedSucc, BasicBlock &NormalSucc, bool InsertFreeze) {
+ BasicBlock &UnswitchedSucc, BasicBlock &NormalSucc, bool InsertFreeze,
+ Instruction *I, AssumptionCache *AC, DominatorTree &DT) {
IRBuilder<> IRB(&BB);
- Value *Cond = Direction ? IRB.CreateOr(Invariants) :
- IRB.CreateAnd(Invariants);
- if (InsertFreeze)
- Cond = IRB.CreateFreeze(Cond, Cond->getName() + ".fr");
+ SmallVector<Value *> FrozenInvariants;
+ for (Value *Inv : Invariants) {
+ if (InsertFreeze && !isGuaranteedNotToBeUndefOrPoison(Inv, AC, I, &DT))
+ Inv = IRB.CreateFreeze(Inv, Inv->getName() + ".fr");
+ FrozenInvariants.push_back(Inv);
+ }
+
+ Value *Cond = Direction ? IRB.CreateOr(FrozenInvariants)
+ : IRB.CreateAnd(FrozenInvariants);
IRB.CreateCondBr(Cond, Direction ? &UnswitchedSucc : &NormalSucc,
Direction ? &NormalSucc : &UnswitchedSucc);
}
@@ -572,10 +578,7 @@ static bool unswitchTrivialBranch(Loop &L, BranchInst &BI, DominatorTree &DT,
" condition!");
buildPartialUnswitchConditionalBranch(
*OldPH, Invariants, ExitDirection, *UnswitchedBB, *NewPH,
- FreezeLoopUnswitchCond && any_of(Invariants, [&](Value *C) {
- return !isGuaranteedNotToBeUndefOrPoison(C, nullptr,
- OldPH->getTerminator(), &DT);
- }));
+ FreezeLoopUnswitchCond, OldPH->getTerminator(), nullptr, DT);
}
// Update the dominator tree with the added edge.
@@ -2318,11 +2321,9 @@ static void unswitchNontrivialInvariants(
buildPartialInvariantUnswitchConditionalBranch(
*SplitBB, Invariants, Direction, *ClonedPH, *LoopPH, L, MSSAU);
else {
- buildPartialUnswitchConditionalBranch(
- *SplitBB, Invariants, Direction, *ClonedPH, *LoopPH,
- InsertFreeze && any_of(Invariants, [&](Value *C) {
- return !isGuaranteedNotToBeUndefOrPoison(C, &AC, BI, &DT);
- }));
+ buildPartialUnswitchConditionalBranch(*SplitBB, Invariants, Direction,
+ *ClonedPH, *LoopPH, InsertFreeze,
+ BI, &AC, DT);
}
DTUpdates.push_back({DominatorTree::Insert, SplitBB, ClonedPH});
diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-freeze-individual-conditions.ll b/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-freeze-individual-conditions.ll
index b135e28754838..831dd5f6c0394 100644
--- a/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-freeze-individual-conditions.ll
+++ b/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-freeze-individual-conditions.ll
@@ -6,13 +6,15 @@ declare void @some_func()
define i32 @need_freeze_of_individual_or_conditions1(i1 %cond1, i1 %cond2, i1 %cond3, i1 %cond4) {
; CHECK-LABEL: @need_freeze_of_individual_or_conditions1(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[COND4:%.*]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP0]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[ENTRY_SPLIT:%.*]], label [[EXIT_SPLIT:%.*]]
+; CHECK-NEXT: [[COND4_FR:%.*]] = freeze i1 [[COND4:%.*]]
+; CHECK-NEXT: [[COND1_FR:%.*]] = freeze i1 [[COND1:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[COND4_FR]], [[COND1_FR]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[ENTRY_SPLIT:%.*]], label [[EXIT_SPLIT:%.*]]
; CHECK: entry.split:
-; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[COND2:%.*]], [[COND3:%.*]]
-; CHECK-NEXT: [[DOTFR2:%.*]] = freeze i1 [[TMP1]]
-; CHECK-NEXT: br i1 [[DOTFR2]], label [[ENTRY_SPLIT_SPLIT:%.*]], label [[EXIT_SPLIT1:%.*]]
+; CHECK-NEXT: [[COND2_FR:%.*]] = freeze i1 [[COND2:%.*]]
+; CHECK-NEXT: [[COND3_FR:%.*]] = freeze i1 [[COND3:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[COND2_FR]], [[COND3_FR]]
+; CHECK-NEXT: br i1 [[TMP1]], label [[ENTRY_SPLIT_SPLIT:%.*]], label [[EXIT_SPLIT1:%.*]]
; CHECK: entry.split.split:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
@@ -50,13 +52,14 @@ exit:
define i32 @need_freeze_of_individual_or_conditions2(i1 noundef %cond1, i1 %cond2, i1 %cond3, i1 %cond4) {
; CHECK-LABEL: @need_freeze_of_individual_or_conditions2(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[COND4:%.*]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP0]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[ENTRY_SPLIT:%.*]], label [[EXIT_SPLIT:%.*]]
+; CHECK-NEXT: [[COND4_FR:%.*]] = freeze i1 [[COND4:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[COND4_FR]], [[COND1:%.*]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[ENTRY_SPLIT:%.*]], label [[EXIT_SPLIT:%.*]]
; CHECK: entry.split:
-; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[COND2:%.*]], [[COND3:%.*]]
-; CHECK-NEXT: [[DOTFR2:%.*]] = freeze i1 [[TMP1]]
-; CHECK-NEXT: br i1 [[DOTFR2]], label [[ENTRY_SPLIT_SPLIT:%.*]], label [[EXIT_SPLIT1:%.*]]
+; CHECK-NEXT: [[COND2_FR:%.*]] = freeze i1 [[COND2:%.*]]
+; CHECK-NEXT: [[COND3_FR:%.*]] = freeze i1 [[COND3:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[COND2_FR]], [[COND3_FR]]
+; CHECK-NEXT: br i1 [[TMP1]], label [[ENTRY_SPLIT_SPLIT:%.*]], label [[EXIT_SPLIT1:%.*]]
; CHECK: entry.split.split:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
@@ -94,13 +97,14 @@ exit:
define i32 @need_freeze_of_individual_or_conditions3(i1 %cond1, i1 %cond2, i1 %cond3, i1 noundef %cond4) {
; CHECK-LABEL: @need_freeze_of_individual_or_conditions3(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[COND4:%.*]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP0]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[ENTRY_SPLIT:%.*]], label [[EXIT_SPLIT:%.*]]
+; CHECK-NEXT: [[COND1_FR:%.*]] = freeze i1 [[COND1:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[COND4:%.*]], [[COND1_FR]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[ENTRY_SPLIT:%.*]], label [[EXIT_SPLIT:%.*]]
; CHECK: entry.split:
-; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[COND2:%.*]], [[COND3:%.*]]
-; CHECK-NEXT: [[DOTFR2:%.*]] = freeze i1 [[TMP1]]
-; CHECK-NEXT: br i1 [[DOTFR2]], label [[ENTRY_SPLIT_SPLIT:%.*]], label [[EXIT_SPLIT1:%.*]]
+; CHECK-NEXT: [[COND2_FR:%.*]] = freeze i1 [[COND2:%.*]]
+; CHECK-NEXT: [[COND3_FR:%.*]] = freeze i1 [[COND3:%.*]]
+; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[COND2_FR]], [[COND3_FR]]
+; CHECK-NEXT: br i1 [[TMP1]], label [[ENTRY_SPLIT_SPLIT:%.*]], label [[EXIT_SPLIT1:%.*]]
; CHECK: entry.split.split:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
@@ -138,9 +142,10 @@ exit:
define i32 @need_freeze_of_individual_and_conditions1(i1 %cond1, i1 %cond4) {
; CHECK-LABEL: @need_freeze_of_individual_and_conditions1(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4:%.*]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP0]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK-NEXT: [[COND4_FR:%.*]] = freeze i1 [[COND4:%.*]]
+; CHECK-NEXT: [[COND1_FR:%.*]] = freeze i1 [[COND1:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4_FR]], [[COND1_FR]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
; CHECK: entry.split:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
@@ -172,9 +177,9 @@ exit:
define i32 @need_freeze_of_individual_and_conditions2(i1 noundef %cond1, i1 %cond4) {
; CHECK-LABEL: @need_freeze_of_individual_and_conditions2(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4:%.*]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP0]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK-NEXT: [[COND4_FR:%.*]] = freeze i1 [[COND4:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4_FR]], [[COND1:%.*]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
; CHECK: entry.split:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
@@ -206,9 +211,9 @@ exit:
define i32 @need_freeze_of_individual_and_conditions3(i1 %cond1, i1 noundef %cond4) {
; CHECK-LABEL: @need_freeze_of_individual_and_conditions3(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4:%.*]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP0]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK-NEXT: [[COND1_FR:%.*]] = freeze i1 [[COND1:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4:%.*]], [[COND1_FR]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
; CHECK: entry.split:
; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
; CHECK: loop.header:
diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-logical-and-or.ll b/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-logical-and-or.ll
index f8fdc1ae46958..320813542dae3 100644
--- a/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-logical-and-or.ll
+++ b/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch-logical-and-or.ll
@@ -152,11 +152,14 @@ exit:
define i32 @test_partial_condition_unswitch_or_select(i32* %var, i1 %cond1, i1 %cond2, i1 %cond3, i1 %cond4, i1 %cond5, i1 %cond6) {
; CHECK-LABEL: @test_partial_condition_unswitch_or_select(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4:%.*]], [[COND2:%.*]]
-; CHECK-NEXT: [[TMP1:%.*]] = or i1 [[TMP0]], [[COND3:%.*]]
-; CHECK-NEXT: [[TMP2:%.*]] = or i1 [[TMP1]], [[COND1:%.*]]
-; CHECK-NEXT: [[DOTFR:%.*]] = freeze i1 [[TMP2]]
-; CHECK-NEXT: br i1 [[DOTFR]], label [[LOOP_EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK-NEXT: [[COND4_FR:%.*]] = freeze i1 [[COND4:%.*]]
+; CHECK-NEXT: [[COND2_FR:%.*]] = freeze i1 [[COND2:%.*]]
+; CHECK-NEXT: [[COND3_FR:%.*]] = freeze i1 [[COND3:%.*]]
+; CHECK-NEXT: [[COND1_FR:%.*]] = freeze i1 [[COND1:%.*]]
+; CHECK-NEXT: [[TMP0:%.*]] = or i1 [[COND4_FR]], [[COND2_FR]]
+; CHECK-NEXT: [[TMP1:%.*]] = or i1 [[TMP0]], [[COND3_FR]]
+; CHECK-NEXT: [[TMP2:%.*]] = or i1 [[TMP1]], [[COND1_FR]]
+; CHECK-NEXT: br i1 [[TMP2]], label [[LOOP_EXIT_SPLIT:%.*]], label [[ENTRY_SPLIT:%.*]]
; CHECK: entry.split:
; CHECK-NEXT: [[COND6_FR:%.*]] = freeze i1 [[COND6:%.*]]
; CHECK-NEXT: br i1 [[COND6_FR]], label [[LOOP_EXIT_SPLIT1:%.*]], label [[ENTRY_SPLIT_SPLIT:%.*]]
diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch.ll b/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch.ll
index c6962387ccf39..4bb5fc288e1ec 100644
--- a/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch.ll
+++ b/llvm/test/Transforms/SimpleLoopUnswitch/trivial-unswitch.ll
@@ -591,11 +591,14 @@ define i32 @test_partial_condition_unswitch_or(i32* %var, i1 %cond1, i1 %cond2,
entry:
br label %loop_begin
; CHECK-NEXT: entry:
-; CHECK-NEXT: %[[INV_OR1:.*]] = or i1 %cond4, %cond2
-; CHECK-NEXT: %[[INV_OR2:.*]] = or i1 %[[INV_OR1]], %cond3
-; CHECK-NEXT: %[[INV_OR3:.*]] = or i1 %[[INV_OR2]], %cond1
-; CHECK-NEXT: [[FROZEN:%.+]] = freeze i1 %[[INV_OR3]]
-; CHECK-NEXT: br i1 [[FROZEN]], label %loop_exit.split, label %entry.split
+; CHECK-NEXT: %[[C4_FR:.+]] = freeze i1 %cond4
+; CHECK-NEXT: %[[C2_FR:.+]] = freeze i1 %cond2
+; CHECK-NEXT: %[[C3_FR:.+]] = freeze i1 %cond3
+; CHECK-NEXT: %[[C1_FR:.+]] = freeze i1 %cond1
+; CHECK-NEXT: %[[INV_OR1:.*]] = or i1 %[[C4_FR]], %[[C2_FR]]
+; CHECK-NEXT: %[[INV_OR2:.*]] = or i1 %[[INV_OR1]], %[[C3_FR]]
+; CHECK-NEXT: %[[INV_OR3:.*]] = or i1 %[[INV_OR2]], %[[C1_FR]]
+; CHECK-NEXT: br i1 %[[INV_OR3]], label %loop_exit.split, label %entry.split
;
; CHECK: entry.split:
; CHECK-NEXT: br label %loop_begin
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