[llvm] 653fa0b - Do actual DCE in LoopUnroll (try 2)
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Fri May 14 10:47:00 PDT 2021
Author: Philip Reames
Date: 2021-05-14T10:42:36-07:00
New Revision: 653fa0b46ae34c06495b542414b704b30381cd02
URL: https://github.com/llvm/llvm-project/commit/653fa0b46ae34c06495b542414b704b30381cd02
DIFF: https://github.com/llvm/llvm-project/commit/653fa0b46ae34c06495b542414b704b30381cd02.diff
LOG: Do actual DCE in LoopUnroll (try 2)
Recommitting after addressing a missed review comment, and updating an aarch64 test I'd missed.
LoopUnroll does a limited DCE pass after unrolling, but if you have a chain of dead instructions, it only deletes the last one. Improve the code to recursively delete all trivially dead instructions.
Differential Revision: https://reviews.llvm.org/D102511
Added:
Modified:
llvm/lib/Transforms/Utils/LoopUnroll.cpp
llvm/test/Transforms/LoopUnroll/AArch64/full-unroll-trip-count-upper-bound.ll
llvm/test/Transforms/LoopUnroll/nonlatchcondbr.ll
llvm/test/Transforms/LoopUnroll/optsize-loop-size.ll
llvm/test/Transforms/LoopUnroll/pr45939-peel-count-and-complete-unroll.ll
llvm/test/Transforms/LoopUnroll/scevunroll.ll
llvm/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
llvm/test/Transforms/LoopUnroll/unroll-unconditional-latch.ll
llvm/test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index 893b918010e11..1837fb6b5a917 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -213,16 +213,11 @@ void llvm::simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
// Aggressively clean up dead instructions that simplifyLoopIVs already
// identified. Any remaining should be cleaned up below.
- while (!DeadInsts.empty()) {
- Value *V = DeadInsts.pop_back_val();
- if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
- RecursivelyDeleteTriviallyDeadInstructions(Inst);
- }
+ RecursivelyDeleteTriviallyDeadInstructions(DeadInsts);
}
- // At this point, the code is well formed. We now do a quick sweep over the
- // inserted code, doing constant propagation and dead code elimination as we
- // go.
+ // At this point, the code is well formed. Perform constprop, instsimplify,
+ // and dce.
const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
for (BasicBlock *BB : L->getBlocks()) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
@@ -232,14 +227,9 @@ void llvm::simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI,
if (LI->replacementPreservesLCSSAForm(Inst, V))
Inst->replaceAllUsesWith(V);
if (isInstructionTriviallyDead(Inst))
- BB->getInstList().erase(Inst);
+ RecursivelyDeleteTriviallyDeadInstructions(Inst);
}
}
-
- // TODO: after peeling or unrolling, previously loop variant conditions are
- // likely to fold to constants, eagerly propagating those here will require
- // fewer cleanup passes to be run. Alternatively, a LoopEarlyCSE might be
- // appropriate.
}
/// Unroll the given loop by Count. The loop must be in LCSSA form. Unrolling
diff --git a/llvm/test/Transforms/LoopUnroll/AArch64/full-unroll-trip-count-upper-bound.ll b/llvm/test/Transforms/LoopUnroll/AArch64/full-unroll-trip-count-upper-bound.ll
index 5c70a2668db15..b924d74166d78 100644
--- a/llvm/test/Transforms/LoopUnroll/AArch64/full-unroll-trip-count-upper-bound.ll
+++ b/llvm/test/Transforms/LoopUnroll/AArch64/full-unroll-trip-count-upper-bound.ll
@@ -11,12 +11,13 @@
; }
;
; This test is meant to check that this loop is unrolled into four iterations.
+; Note that the load on the last iteration is dead and thus doesn't appear in
+; the output.
; UNROLL-LABEL: @test
; UNROLL: load i32, i32*
; UNROLL: load i32, i32*
; UNROLL: load i32, i32*
-; UNROLL: load i32, i32*
; UNROLL-NOT: load i32, i32*
; NOUNROLL-LABEL: @test
; NOUNROLL: load i32, i32*
diff --git a/llvm/test/Transforms/LoopUnroll/nonlatchcondbr.ll b/llvm/test/Transforms/LoopUnroll/nonlatchcondbr.ll
index b433ebb4d6420..995d5de0cdf79 100644
--- a/llvm/test/Transforms/LoopUnroll/nonlatchcondbr.ll
+++ b/llvm/test/Transforms/LoopUnroll/nonlatchcondbr.ll
@@ -40,7 +40,6 @@ define void @test1(i32* noalias %A) {
; CHECK: for.body.3:
; CHECK-NEXT: br i1 false, label [[FOR_BODY_FOR_BODY_CRIT_EDGE_3:%.*]], label [[FOR_END:%.*]]
; CHECK: for.body.for.body_crit_edge.3:
-; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_3:%.*]] = getelementptr inbounds i32, i32* [[A]], i64 4
; CHECK-NEXT: unreachable
;
entry:
@@ -124,7 +123,7 @@ define void @test2(i32* noalias %A) {
; CHECK: for.body.for.body_crit_edge.3:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_3:%.*]] = getelementptr inbounds i32, i32* [[A]], i64 [[INC_3]]
; CHECK-NEXT: [[DOTPRE_3]] = load i32, i32* [[ARRAYIDX_PHI_TRANS_INSERT_3]], align 4
-; CHECK-NEXT: br label [[FOR_HEADER]], !llvm.loop !0
+; CHECK-NEXT: br label [[FOR_HEADER]], !llvm.loop [[LOOP0:![0-9]+]]
;
entry:
br i1 true, label %for.preheader, label %for.end
@@ -202,7 +201,7 @@ define void @test3(i32* noalias %A, i1 %cond) {
; CHECK: for.body.for.body_crit_edge.3:
; CHECK-NEXT: [[ARRAYIDX_PHI_TRANS_INSERT_3:%.*]] = getelementptr inbounds i32, i32* [[A]], i64 [[INC_3]]
; CHECK-NEXT: [[DOTPRE_3]] = load i32, i32* [[ARRAYIDX_PHI_TRANS_INSERT_3]], align 4
-; CHECK-NEXT: br label [[FOR_HEADER]], !llvm.loop !2
+; CHECK-NEXT: br label [[FOR_HEADER]], !llvm.loop [[LOOP2:![0-9]+]]
;
entry:
%0 = load i32, i32* %A, align 4
diff --git a/llvm/test/Transforms/LoopUnroll/optsize-loop-size.ll b/llvm/test/Transforms/LoopUnroll/optsize-loop-size.ll
index 4ca397a1c770e..659c7cf9af37a 100644
--- a/llvm/test/Transforms/LoopUnroll/optsize-loop-size.ll
+++ b/llvm/test/Transforms/LoopUnroll/optsize-loop-size.ll
@@ -12,7 +12,6 @@ define i32 @test(i32 %a, i32 %b, i32 %c) optsize {
; CHECK-NEXT: store i32 [[B:%.*]], i32* [[ARRAYINIT_ELEMENT]], align 4
; CHECK-NEXT: [[ARRAYINIT_ELEMENT1:%.*]] = getelementptr inbounds [3 x i32], [3 x i32]* [[REF_TMP]], i64 0, i64 2
; CHECK-NEXT: store i32 [[C:%.*]], i32* [[ARRAYINIT_ELEMENT1]], align 4
-; CHECK-NEXT: [[ADD_PTR_I_I:%.*]] = getelementptr inbounds [3 x i32], [3 x i32]* [[REF_TMP]], i64 0, i64 3
; CHECK-NEXT: [[CMP_I_I_I3:%.*]] = icmp slt i32 [[A]], [[B]]
; CHECK-NEXT: [[SPEC_SELECT_I_I4:%.*]] = select i1 [[CMP_I_I_I3]], i32* [[ARRAYINIT_ELEMENT]], i32* [[ARRAYINIT_BEGIN]]
; CHECK-NEXT: [[INCDEC_PTR_I_I5:%.*]] = getelementptr inbounds [3 x i32], [3 x i32]* [[REF_TMP]], i64 0, i64 2
@@ -22,7 +21,6 @@ define i32 @test(i32 %a, i32 %b, i32 %c) optsize {
; CHECK-NEXT: [[DOTPRE2:%.*]] = load i32, i32* [[INCDEC_PTR_I_I5]], align 4
; CHECK-NEXT: [[CMP_I_I_I:%.*]] = icmp slt i32 [[DOTPRE]], [[DOTPRE2]]
; CHECK-NEXT: [[SPEC_SELECT_I_I:%.*]] = select i1 [[CMP_I_I_I]], i32* [[INCDEC_PTR_I_I5]], i32* [[SPEC_SELECT_I_I4]]
-; CHECK-NEXT: [[INCDEC_PTR_I_I:%.*]] = getelementptr inbounds i32, i32* [[INCDEC_PTR_I_I5]], i64 1
; CHECK-NEXT: [[TMP1:%.*]] = load i32, i32* [[SPEC_SELECT_I_I]], align 4
; CHECK-NEXT: ret i32 [[TMP1]]
;
diff --git a/llvm/test/Transforms/LoopUnroll/pr45939-peel-count-and-complete-unroll.ll b/llvm/test/Transforms/LoopUnroll/pr45939-peel-count-and-complete-unroll.ll
index 633a2d24baf9a..d7325692fab32 100644
--- a/llvm/test/Transforms/LoopUnroll/pr45939-peel-count-and-complete-unroll.ll
+++ b/llvm/test/Transforms/LoopUnroll/pr45939-peel-count-and-complete-unroll.ll
@@ -163,7 +163,6 @@ define void @test1() {
; PEEL8-NEXT: [[ARRAYIDX_7:%.*]] = getelementptr inbounds [8 x i32], [8 x i32]* @a, i64 0, i64 [[INDVARS_IV_NEXT_6]]
; PEEL8-NEXT: [[TMP15:%.*]] = trunc i64 [[INDVARS_IV_NEXT_6]] to i32
; PEEL8-NEXT: store i32 [[TMP15]], i32* [[ARRAYIDX_7]], align 4
-; PEEL8-NEXT: [[INDVARS_IV_NEXT_7:%.*]] = add nuw nsw i64 [[INDVARS_IV_NEXT_6]], 1
; PEEL8-NEXT: br label [[FOR_EXIT]]
; PEEL8: for.exit:
; PEEL8-NEXT: ret void
@@ -206,7 +205,7 @@ define void @test1() {
; PEEL2UNROLL2-NEXT: store i32 [[TMP3]], i32* [[ARRAYIDX_1]], align 4
; PEEL2UNROLL2-NEXT: [[INDVARS_IV_NEXT_1]] = add nuw nsw i64 [[INDVARS_IV_NEXT]], 1
; PEEL2UNROLL2-NEXT: [[EXITCOND_1:%.*]] = icmp ne i64 [[INDVARS_IV_NEXT_1]], 8
-; PEEL2UNROLL2-NEXT: br i1 [[EXITCOND_1]], label [[FOR_BODY]], label [[FOR_EXIT_LOOPEXIT:%.*]], !llvm.loop !0
+; PEEL2UNROLL2-NEXT: br i1 [[EXITCOND_1]], label [[FOR_BODY]], label [[FOR_EXIT_LOOPEXIT:%.*]], !llvm.loop [[LOOP0:![0-9]+]]
; PEEL2UNROLL2: for.exit.loopexit:
; PEEL2UNROLL2-NEXT: br label [[FOR_EXIT]]
; PEEL2UNROLL2: for.exit:
diff --git a/llvm/test/Transforms/LoopUnroll/scevunroll.ll b/llvm/test/Transforms/LoopUnroll/scevunroll.ll
index 4d9ae39f721f7..566dbeb5fcd21 100644
--- a/llvm/test/Transforms/LoopUnroll/scevunroll.ll
+++ b/llvm/test/Transforms/LoopUnroll/scevunroll.ll
@@ -10,7 +10,6 @@
define i32 @sansCanonical(i32* %base) nounwind {
; CHECK-LABEL: @sansCanonical(
; CHECK-NEXT: entry:
-; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 0 to i64
; CHECK-NEXT: br label [[WHILE_BODY:%.*]]
; CHECK: while.body:
; CHECK-NEXT: [[ADR:%.*]] = getelementptr inbounds i32, i32* [[BASE:%.*]], i64 9
@@ -39,7 +38,6 @@ define i32 @sansCanonical(i32* %base) nounwind {
; CHECK-NEXT: [[ADR_8:%.*]] = getelementptr inbounds i32, i32* [[BASE]], i64 1
; CHECK-NEXT: [[TMP_8:%.*]] = load i32, i32* [[ADR_8]], align 8
; CHECK-NEXT: [[SUM_NEXT_8:%.*]] = add i32 [[SUM_NEXT_7]], [[TMP_8]]
-; CHECK-NEXT: [[TMP_9:%.*]] = load i32, i32* [[BASE]], align 8
; CHECK-NEXT: ret i32 [[SUM_NEXT_8]]
;
entry:
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll b/llvm/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
index 4bbae7e83e9b9..5b37298033035 100644
--- a/llvm/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
+++ b/llvm/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
@@ -10,23 +10,18 @@ define i16 @full_unroll(i16* %A) {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
-; CHECK-NEXT: [[TMP2:%.*]] = load i16, i16* [[A:%.*]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3:%.*]]
; CHECK: for.cond.cleanup:
; CHECK-NEXT: [[DOTLCSSA10_LCSSA:%.*]] = phi i16 [ [[TMP2_2:%.*]], [[FOR_COND_CLEANUP3_2:%.*]] ]
; CHECK-NEXT: [[TMP3:%.*]] = call i16 @func(i16 [[DOTLCSSA10_LCSSA]])
; CHECK-NEXT: ret i16 0
; CHECK: for.cond.cleanup3:
-; CHECK-NEXT: [[PTR_1:%.*]] = getelementptr inbounds i16, i16* [[A]], i64 1
-; CHECK-NEXT: [[TMP2_1:%.*]] = load i16, i16* [[PTR_1]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3_1:%.*]]
; CHECK: for.cond.cleanup3.1:
-; CHECK-NEXT: [[PTR_2:%.*]] = getelementptr inbounds i16, i16* [[A]], i64 2
+; CHECK-NEXT: [[PTR_2:%.*]] = getelementptr inbounds i16, i16* [[A:%.*]], i64 2
; CHECK-NEXT: [[TMP2_2]] = load i16, i16* [[PTR_2]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3_2]]
; CHECK: for.cond.cleanup3.2:
-; CHECK-NEXT: [[PTR_3:%.*]] = getelementptr inbounds i16, i16* [[A]], i64 3
-; CHECK-NEXT: [[TMP2_3:%.*]] = load i16, i16* [[PTR_3]], align 2
; CHECK-NEXT: br i1 false, label [[FOR_COND_CLEANUP3_3:%.*]], label [[FOR_COND_CLEANUP:%.*]]
; CHECK: for.cond.cleanup3.3:
; CHECK-NEXT: unreachable
@@ -59,8 +54,6 @@ define i16 @partial_unroll(i16* %A) {
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[I_0:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC9_2:%.*]], [[FOR_COND_CLEANUP3_2:%.*]] ]
-; CHECK-NEXT: [[PTR:%.*]] = getelementptr inbounds i16, i16* [[A:%.*]], i64 [[I_0]]
-; CHECK-NEXT: [[TMP2:%.*]] = load i16, i16* [[PTR]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3:%.*]]
; CHECK: for.cond.cleanup:
; CHECK-NEXT: [[DOTLCSSA10_LCSSA:%.*]] = phi i16 [ [[TMP2_1:%.*]], [[FOR_COND_CLEANUP3_1:%.*]] ]
@@ -68,13 +61,11 @@ define i16 @partial_unroll(i16* %A) {
; CHECK-NEXT: ret i16 0
; CHECK: for.cond.cleanup3:
; CHECK-NEXT: [[INC9:%.*]] = add nuw nsw i64 [[I_0]], 1
-; CHECK-NEXT: [[PTR_1:%.*]] = getelementptr inbounds i16, i16* [[A]], i64 [[INC9]]
+; CHECK-NEXT: [[PTR_1:%.*]] = getelementptr inbounds i16, i16* [[A:%.*]], i64 [[INC9]]
; CHECK-NEXT: [[TMP2_1]] = load i16, i16* [[PTR_1]], align 2
; CHECK-NEXT: br label [[FOR_COND_CLEANUP3_1]]
; CHECK: for.cond.cleanup3.1:
; CHECK-NEXT: [[INC9_1:%.*]] = add nuw nsw i64 [[INC9]], 1
-; CHECK-NEXT: [[PTR_2:%.*]] = getelementptr inbounds i16, i16* [[A]], i64 [[INC9_1]]
-; CHECK-NEXT: [[TMP2_2:%.*]] = load i16, i16* [[PTR_2]], align 2
; CHECK-NEXT: [[CMP_2:%.*]] = icmp ult i64 [[INC9_1]], 200
; CHECK-NEXT: br i1 [[CMP_2]], label [[FOR_COND_CLEANUP3_2]], label [[FOR_COND_CLEANUP:%.*]]
; CHECK: for.cond.cleanup3.2:
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-unconditional-latch.ll b/llvm/test/Transforms/LoopUnroll/unroll-unconditional-latch.ll
index 89d1144314b48..4970a9080940f 100644
--- a/llvm/test/Transforms/LoopUnroll/unroll-unconditional-latch.ll
+++ b/llvm/test/Transforms/LoopUnroll/unroll-unconditional-latch.ll
@@ -68,7 +68,6 @@ define double @test_with_lcssa(double %arg1, double* %arg2) {
; CHECK-NEXT: [[RES_LCSSA:%.*]] = phi double [ [[RES_1]], [[LOOP_LATCH]] ]
; CHECK-NEXT: ret double [[RES_LCSSA]]
; CHECK: loop.latch.1:
-; CHECK-NEXT: [[PTR_1:%.*]] = getelementptr inbounds double, double* [[ARG2]], i64 2
; CHECK-NEXT: unreachable
;
diff --git a/llvm/test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll b/llvm/test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll
index 5086b2019ced0..88fdd43fafff6 100644
--- a/llvm/test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll
+++ b/llvm/test/Transforms/LoopUnrollAndJam/unroll-and-jam.ll
@@ -141,8 +141,6 @@ target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
; CHECK-NEXT: [[ADD_LCSSA_EPIL_2:%.*]] = phi i32 [ [[ADD_EPIL_2]], [[FOR_INNER_EPIL_2]] ]
; CHECK-NEXT: [[ARRAYIDX6_EPIL_2:%.*]] = getelementptr inbounds i32, i32* [[A]], i32 [[ADD8_EPIL_1]]
; CHECK-NEXT: store i32 [[ADD_LCSSA_EPIL_2]], i32* [[ARRAYIDX6_EPIL_2]], align 4, !tbaa !0
-; CHECK-NEXT: [[ADD8_EPIL_2:%.*]] = add nuw i32 [[ADD8_EPIL_1]], 1
-; CHECK-NEXT: [[EPIL_ITER_SUB_2:%.*]] = sub i32 [[EPIL_ITER_SUB_1]], 1
; CHECK-NEXT: br label [[FOR_END_LOOPEXIT_EPILOG_LCSSA]]
define void @test1(i32 %I, i32 %J, i32* noalias nocapture %A, i32* noalias nocapture readonly %B) #0 {
entry:
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