fa4cc9ddd5
[FixIrreducible] Use CycleInfo instead of a custom SCC traversal 1. CycleInfo efficiently locates all cycles in a single pass, while the SCC is repeated inside every natural loop. 2. CycleInfo provides a hierarchy of irreducible cycles, and the new implementation transforms each cycle in this hierarchy separately instead of reducing an entire irreducible SCC in a single step. This reduces the number of control-flow paths that pass through the header of each newly created loop. This is evidenced by the reduced number of predecessors on the "guard" blocks in the lit tests, and fewer operands on the corresponding PHI nodes. 3. When an entry of an irreducible cycle is the header of a child natural loop, the original implementation destroyed that loop. This is now preserved, since the incoming edges on non-header entries are not touched. 4. In the new implementation, if an irreducible cycle is a superset of a natural loop with the same header, then that natural loop is destroyed and replaced by the newly created loop.
280 lines
9.6 KiB
LLVM
280 lines
9.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -fix-irreducible --verify-loop-info -S | FileCheck %s
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; RUN: opt < %s -passes='fix-irreducible,verify<loops>' -S | FileCheck %s
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; RUN: opt < %s -passes='verify<loops>,fix-irreducible,verify<loops>' -S | FileCheck %s
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define i32 @basic(i1 %PredEntry, i1 %PredLeft, i1 %PredRight, i32 %X, i32 %Y) {
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; CHECK-LABEL: @basic(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[PREDENTRY_INV:%.*]] = xor i1 [[PREDENTRY:%.*]], true
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; CHECK-NEXT: br label [[IRR_GUARD:%.*]]
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; CHECK: left:
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; CHECK-NEXT: [[L_PHI:%.*]] = phi i32 [ [[R_PHI_MOVED:%.*]], [[RIGHT:%.*]] ], [ [[L_PHI_MOVED:%.*]], [[IRR_GUARD]] ]
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; CHECK-NEXT: [[L:%.*]] = add i32 [[L_PHI]], 1
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; CHECK-NEXT: br i1 [[PREDLEFT:%.*]], label [[IRR_GUARD]], label [[EXIT:%.*]]
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; CHECK: right:
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; CHECK-NEXT: br i1 [[PREDRIGHT:%.*]], label [[LEFT:%.*]], label [[EXIT]]
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; CHECK: exit:
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; CHECK-NEXT: [[Z:%.*]] = phi i32 [ [[L]], [[LEFT]] ], [ [[R_PHI_MOVED]], [[RIGHT]] ]
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; CHECK-NEXT: ret i32 [[Z]]
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; CHECK: irr.guard:
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; CHECK-NEXT: [[L_PHI_MOVED]] = phi i32 [ [[L_PHI_MOVED]], [[LEFT]] ], [ [[X:%.*]], [[ENTRY:%.*]] ]
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; CHECK-NEXT: [[R_PHI_MOVED]] = phi i32 [ [[L]], [[LEFT]] ], [ [[Y:%.*]], [[ENTRY]] ]
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; CHECK-NEXT: [[GUARD_RIGHT:%.*]] = phi i1 [ true, [[LEFT]] ], [ [[PREDENTRY_INV]], [[ENTRY]] ]
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; CHECK-NEXT: br i1 [[GUARD_RIGHT]], label [[RIGHT]], label [[LEFT]]
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;
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entry:
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br i1 %PredEntry, label %left, label %right
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left:
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%L.phi = phi i32 [%X, %entry], [%R.phi, %right]
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%L = add i32 %L.phi, 1
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br i1 %PredLeft, label %right, label %exit
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right:
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%R.phi = phi i32 [%Y, %entry], [%L, %left]
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br i1 %PredRight, label %left, label %exit
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exit:
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%Z = phi i32 [%L, %left], [%R.phi, %right]
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ret i32 %Z
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}
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define i32 @feedback_loop(i1 %PredEntry, i1 %PredLeft, i1 %PredRight, i32 %X, i32 %Y) {
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; CHECK-LABEL: @feedback_loop(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[PREDENTRY_INV:%.*]] = xor i1 [[PREDENTRY:%.*]], true
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; CHECK-NEXT: br label [[IRR_GUARD:%.*]]
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; CHECK: left:
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; CHECK-NEXT: [[L_PHI:%.*]] = phi i32 [ [[R_PHI_MOVED:%.*]], [[RIGHT:%.*]] ], [ [[L_PHI_MOVED:%.*]], [[IRR_GUARD]] ]
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; CHECK-NEXT: br i1 [[PREDLEFT:%.*]], label [[IRR_GUARD]], label [[EXIT:%.*]]
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; CHECK: right:
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; CHECK-NEXT: br i1 [[PREDRIGHT:%.*]], label [[LEFT:%.*]], label [[EXIT]]
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; CHECK: exit:
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; CHECK-NEXT: [[Z:%.*]] = phi i32 [ [[L_PHI]], [[LEFT]] ], [ [[R_PHI_MOVED]], [[RIGHT]] ]
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; CHECK-NEXT: ret i32 [[Z]]
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; CHECK: irr.guard:
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; CHECK-NEXT: [[L_PHI_MOVED]] = phi i32 [ [[L_PHI_MOVED]], [[LEFT]] ], [ [[X:%.*]], [[ENTRY:%.*]] ]
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; CHECK-NEXT: [[R_PHI_MOVED]] = phi i32 [ [[L_PHI]], [[LEFT]] ], [ [[Y:%.*]], [[ENTRY]] ]
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; CHECK-NEXT: [[GUARD_RIGHT:%.*]] = phi i1 [ true, [[LEFT]] ], [ [[PREDENTRY_INV]], [[ENTRY]] ]
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; CHECK-NEXT: br i1 [[GUARD_RIGHT]], label [[RIGHT]], label [[LEFT]]
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;
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entry:
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br i1 %PredEntry, label %left, label %right
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left:
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%L.phi = phi i32 [%X, %entry], [%R.phi, %right]
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br i1 %PredLeft, label %right, label %exit
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right:
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%R.phi = phi i32 [%Y, %entry], [%L.phi, %left]
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br i1 %PredRight, label %left, label %exit
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exit:
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%Z = phi i32 [%L.phi, %left], [%R.phi, %right]
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ret i32 %Z
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}
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define i32 @multiple_predecessors(i1 %PredEntry, i1 %PredA, i1 %PredB, i1 %PredC, i1 %PredD, i32 %X, i32 %Y) {
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; CHECK-LABEL: @multiple_predecessors(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[PREDB_INV:%.*]] = xor i1 [[PREDB:%.*]], true
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; CHECK-NEXT: br i1 [[PREDENTRY:%.*]], label [[A:%.*]], label [[B:%.*]]
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; CHECK: A:
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; CHECK-NEXT: [[A_INC:%.*]] = add i32 [[X:%.*]], 1
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; CHECK-NEXT: br label [[IRR_GUARD:%.*]]
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; CHECK: B:
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; CHECK-NEXT: br label [[IRR_GUARD]]
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; CHECK: C:
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; CHECK-NEXT: br i1 [[PREDC:%.*]], label [[D:%.*]], label [[EXIT:%.*]]
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; CHECK: D:
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; CHECK-NEXT: [[D_PHI:%.*]] = phi i32 [ [[C_PHI_MOVED:%.*]], [[C:%.*]] ], [ [[D_PHI_MOVED:%.*]], [[IRR_GUARD]] ]
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; CHECK-NEXT: [[D_INC:%.*]] = add i32 [[D_PHI]], 1
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; CHECK-NEXT: br i1 [[PREDD:%.*]], label [[EXIT]], label [[IRR_GUARD]]
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; CHECK: exit:
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; CHECK-NEXT: [[RET:%.*]] = phi i32 [ [[C_PHI_MOVED]], [[C]] ], [ [[D_INC]], [[D]] ]
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; CHECK-NEXT: ret i32 [[RET]]
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; CHECK: irr.guard:
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; CHECK-NEXT: [[D_PHI_MOVED]] = phi i32 [ [[D_PHI_MOVED]], [[D]] ], [ [[Y:%.*]], [[B]] ], [ [[A_INC]], [[A]] ]
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; CHECK-NEXT: [[C_PHI_MOVED]] = phi i32 [ [[D_INC]], [[D]] ], [ [[Y]], [[B]] ], [ [[X]], [[A]] ]
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; CHECK-NEXT: [[GUARD_C:%.*]] = phi i1 [ true, [[D]] ], [ [[PREDB_INV]], [[B]] ], [ [[PREDA:%.*]], [[A]] ]
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; CHECK-NEXT: br i1 [[GUARD_C]], label [[C]], label [[D]]
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;
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entry:
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br i1 %PredEntry, label %A, label %B
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A:
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%A.inc = add i32 %X, 1
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br i1 %PredA, label %C, label %D
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B:
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br i1 %PredB, label %D, label %C
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C:
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%C.phi = phi i32 [%X, %A], [%Y, %B], [%D.inc, %D]
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br i1 %PredC, label %D, label %exit
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D:
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%D.phi = phi i32 [%A.inc, %A], [%Y, %B], [%C.phi, %C]
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%D.inc = add i32 %D.phi, 1
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br i1 %PredD, label %exit, label %C
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exit:
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%ret = phi i32 [%C.phi, %C], [%D.inc, %D]
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ret i32 %ret
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}
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define i32 @separate_predecessors(i1 %PredEntry, i1 %PredA, i1 %PredB, i1 %PredC, i1 %PredD, i32 %X, i32 %Y) {
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; CHECK-LABEL: @separate_predecessors(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br i1 [[PREDENTRY:%.*]], label [[A:%.*]], label [[B:%.*]]
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; CHECK: A:
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; CHECK-NEXT: [[A_INC:%.*]] = add i32 [[X:%.*]], 1
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; CHECK-NEXT: br label [[IRR_GUARD:%.*]]
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; CHECK: B:
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; CHECK-NEXT: br label [[IRR_GUARD]]
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; CHECK: C:
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; CHECK-NEXT: [[C_PHI:%.*]] = phi i32 [ [[D_INC:%.*]], [[D:%.*]] ], [ [[C_PHI_MOVED:%.*]], [[IRR_GUARD]] ]
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; CHECK-NEXT: br i1 [[PREDC:%.*]], label [[EXIT:%.*]], label [[IRR_GUARD]]
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; CHECK: D:
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; CHECK-NEXT: [[D_INC]] = add i32 [[D_PHI_MOVED:%.*]], 1
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; CHECK-NEXT: br i1 [[PREDD:%.*]], label [[EXIT]], label [[C:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: [[RET:%.*]] = phi i32 [ [[C_PHI]], [[C]] ], [ [[D_INC]], [[D]] ]
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; CHECK-NEXT: ret i32 [[RET]]
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; CHECK: irr.guard:
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; CHECK-NEXT: [[C_PHI_MOVED]] = phi i32 [ [[C_PHI_MOVED]], [[C]] ], [ poison, [[B]] ], [ [[X]], [[A]] ]
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; CHECK-NEXT: [[D_PHI_MOVED]] = phi i32 [ [[C_PHI]], [[C]] ], [ [[Y:%.*]], [[B]] ], [ poison, [[A]] ]
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; CHECK-NEXT: [[GUARD_D:%.*]] = phi i1 [ true, [[C]] ], [ true, [[B]] ], [ false, [[A]] ]
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; CHECK-NEXT: br i1 [[GUARD_D]], label [[D]], label [[C]]
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;
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entry:
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br i1 %PredEntry, label %A, label %B
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A:
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%A.inc = add i32 %X, 1
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br label %C
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B:
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br label %D
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C:
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%C.phi = phi i32 [%X, %A], [%D.inc, %D]
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br i1 %PredC, label %exit, label %D
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D:
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%D.phi = phi i32 [%Y, %B], [%C.phi, %C]
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%D.inc = add i32 %D.phi, 1
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br i1 %PredD, label %exit, label %C
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exit:
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%ret = phi i32 [%C.phi, %C], [%D.inc, %D]
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ret i32 %ret
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}
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define void @four_headers(i1 %PredEntry, i1 %PredX, i1 %PredY, i1 %PredD) {
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; CHECK-LABEL: @four_headers(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[PREDY_INV:%.*]] = xor i1 [[PREDY:%.*]], true
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; CHECK-NEXT: br i1 [[PREDENTRY:%.*]], label [[X:%.*]], label [[Y:%.*]]
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; CHECK: X:
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; CHECK-NEXT: br label [[IRR_GUARD:%.*]]
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; CHECK: Y:
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; CHECK-NEXT: br label [[IRR_GUARD]]
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; CHECK: A:
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; CHECK-NEXT: br label [[B:%.*]]
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; CHECK: B:
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; CHECK-NEXT: br label [[C:%.*]]
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; CHECK: C:
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; CHECK-NEXT: br label [[IRR_GUARD]]
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; CHECK: D:
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; CHECK-NEXT: br i1 [[PREDD:%.*]], label [[EXIT:%.*]], label [[A:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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; CHECK: irr.guard:
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; CHECK-NEXT: [[GUARD_D:%.*]] = phi i1 [ true, [[C]] ], [ [[PREDY_INV]], [[Y]] ], [ false, [[X]] ]
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; CHECK-NEXT: [[GUARD_C:%.*]] = phi i1 [ false, [[C]] ], [ true, [[Y]] ], [ false, [[X]] ]
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; CHECK-NEXT: [[GUARD_A:%.*]] = phi i1 [ false, [[C]] ], [ false, [[Y]] ], [ [[PREDX:%.*]], [[X]] ]
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; CHECK-NEXT: br i1 [[GUARD_D]], label [[D:%.*]], label [[IRR_GUARD1:%.*]]
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; CHECK: irr.guard1:
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; CHECK-NEXT: br i1 [[GUARD_C]], label [[C]], label [[IRR_GUARD2:%.*]]
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; CHECK: irr.guard2:
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; CHECK-NEXT: br i1 [[GUARD_A]], label [[A]], label [[B]]
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;
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entry:
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br i1 %PredEntry, label %X, label %Y
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X:
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br i1 %PredX, label %A, label %B
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Y:
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br i1 %PredY, label %C, label %D
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A:
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br label %B
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B:
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br label %C
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C:
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br label %D
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D:
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br i1 %PredD, label %exit, label %A
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exit:
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ret void
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}
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define i32 @hidden_nodes(i1 %PredEntry, i1 %PredA, i1 %PredB, i1 %PredC, i1 %PredD, i32 %X, i32 %Y) {
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; CHECK-LABEL: @hidden_nodes(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[PREDENTRY_INV:%.*]] = xor i1 [[PREDENTRY:%.*]], true
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; CHECK-NEXT: br label [[IRR_GUARD:%.*]]
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; CHECK: A:
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; CHECK-NEXT: [[A_PHI:%.*]] = phi i32 [ [[C_INC:%.*]], [[E:%.*]] ], [ [[A_PHI_MOVED:%.*]], [[IRR_GUARD]] ]
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; CHECK-NEXT: [[A_INC:%.*]] = add i32 [[A_PHI]], 1
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; CHECK-NEXT: br label [[IRR_GUARD]]
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; CHECK: B:
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; CHECK-NEXT: br label [[C:%.*]]
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; CHECK: C:
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; CHECK-NEXT: [[C_INC]] = add i32 [[B_PHI_MOVED:%.*]], 1
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; CHECK-NEXT: br label [[D:%.*]]
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; CHECK: D:
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; CHECK-NEXT: br i1 [[PREDD:%.*]], label [[EXIT:%.*]], label [[E]]
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; CHECK: E:
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; CHECK-NEXT: br label [[A:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret i32 [[B_PHI_MOVED]]
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; CHECK: irr.guard:
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; CHECK-NEXT: [[A_PHI_MOVED]] = phi i32 [ [[A_PHI_MOVED]], [[A]] ], [ [[X:%.*]], [[ENTRY:%.*]] ]
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; CHECK-NEXT: [[B_PHI_MOVED]] = phi i32 [ [[A_INC]], [[A]] ], [ [[Y:%.*]], [[ENTRY]] ]
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; CHECK-NEXT: [[GUARD_B:%.*]] = phi i1 [ true, [[A]] ], [ [[PREDENTRY_INV]], [[ENTRY]] ]
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; CHECK-NEXT: br i1 [[GUARD_B]], label [[B:%.*]], label [[A]]
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;
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entry:
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br i1 %PredEntry, label %A, label %B
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A:
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%A.phi = phi i32 [%X, %entry], [%C.inc, %E]
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%A.inc = add i32 %A.phi, 1
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br label %B
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B:
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%B.phi = phi i32 [%A.inc, %A], [%Y, %entry]
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br label %C
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C:
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%C.inc = add i32 %B.phi, 1
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br label %D
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D:
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br i1 %PredD, label %exit, label %E
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E:
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br label %A
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exit:
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ret i32 %B.phi
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}
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