90ba33099c
This patch canonicalizes getelementptr instructions with constant indices to use the `i8` source element type. This makes it easier for optimizations to recognize that two GEPs are identical, because they don't need to see past many different ways to express the same offset. This is a first step towards https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699. This is limited to constant GEPs only for now, as they have a clear canonical form, while we're not yet sure how exactly to deal with variable indices. The test llvm/test/Transforms/PhaseOrdering/switch_with_geps.ll gives two representative examples of the kind of optimization improvement we expect from this change. In the first test SimplifyCFG can now realize that all switch branches are actually the same. In the second test it can convert it into simple arithmetic. These are representative of common optimization failures we see in Rust. Fixes https://github.com/llvm/llvm-project/issues/69841.
132 lines
6.8 KiB
LLVM
132 lines
6.8 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
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; RUN: opt < %s -S -passes=loop-unroll,simplifycfg,instcombine -unroll-force-peel-count=3 -verify-dom-info -simplifycfg-require-and-preserve-domtree=1 | FileCheck %s
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; RUN: opt < %s -S -passes='require<opt-remark-emit>,loop-unroll,simplifycfg,instcombine' -unroll-force-peel-count=3 -verify-dom-info | FileCheck %s
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; RUN: opt < %s -S -passes='require<opt-remark-emit>,loop-unroll<peeling;no-runtime>,simplifycfg,instcombine' -unroll-force-peel-count=3 -verify-dom-info | FileCheck %s
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; Basic loop peeling - check that we can peel-off the first 3 loop iterations
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; when explicitly requested.
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define void @basic(ptr %p, i32 %k) #0 {
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; CHECK-LABEL: define void @basic(
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; CHECK-SAME: ptr [[P:%.*]], i32 [[K:%.*]]) {
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP3:%.*]] = icmp sgt i32 [[K]], 0
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; CHECK-NEXT: br i1 [[CMP3]], label [[FOR_BODY_PEEL:%.*]], label [[FOR_END:%.*]]
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; CHECK: for.body.peel:
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; CHECK-NEXT: store i32 0, ptr [[P]], align 4
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; CHECK-NEXT: [[CMP_PEEL_NOT:%.*]] = icmp eq i32 [[K]], 1
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; CHECK-NEXT: br i1 [[CMP_PEEL_NOT]], label [[FOR_END]], label [[FOR_BODY_PEEL2:%.*]]
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; CHECK: for.body.peel2:
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; CHECK-NEXT: [[INCDEC_PTR_PEEL:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 4
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; CHECK-NEXT: store i32 1, ptr [[INCDEC_PTR_PEEL]], align 4
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; CHECK-NEXT: [[CMP_PEEL5:%.*]] = icmp sgt i32 [[K]], 2
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; CHECK-NEXT: br i1 [[CMP_PEEL5]], label [[FOR_BODY_PEEL7:%.*]], label [[FOR_END]]
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; CHECK: for.body.peel7:
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; CHECK-NEXT: [[INCDEC_PTR_PEEL3:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 8
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; CHECK-NEXT: [[INCDEC_PTR_PEEL8:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 12
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; CHECK-NEXT: store i32 2, ptr [[INCDEC_PTR_PEEL3]], align 4
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; CHECK-NEXT: [[CMP_PEEL10_NOT:%.*]] = icmp eq i32 [[K]], 3
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; CHECK-NEXT: br i1 [[CMP_PEEL10_NOT]], label [[FOR_END]], label [[FOR_BODY:%.*]]
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; CHECK: for.body:
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; CHECK-NEXT: [[I_05:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ 3, [[FOR_BODY_PEEL7]] ]
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; CHECK-NEXT: [[P_ADDR_04:%.*]] = phi ptr [ [[INCDEC_PTR:%.*]], [[FOR_BODY]] ], [ [[INCDEC_PTR_PEEL8]], [[FOR_BODY_PEEL7]] ]
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; CHECK-NEXT: [[INCDEC_PTR]] = getelementptr inbounds i8, ptr [[P_ADDR_04]], i64 4
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; CHECK-NEXT: store i32 [[I_05]], ptr [[P_ADDR_04]], align 4
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; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I_05]], 1
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; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[INC]], [[K]]
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; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop [[LOOP0:![0-9]+]]
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; CHECK: for.end:
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; CHECK-NEXT: ret void
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;
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entry:
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%cmp3 = icmp slt i32 0, %k
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br i1 %cmp3, label %for.body.lr.ph, label %for.end
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for.body.lr.ph: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.lr.ph, %for.body
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%i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
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%p.addr.04 = phi ptr [ %p, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
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%incdec.ptr = getelementptr inbounds i32, ptr %p.addr.04, i32 1
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store i32 %i.05, ptr %p.addr.04, align 4
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%inc = add nsw i32 %i.05, 1
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%cmp = icmp slt i32 %inc, %k
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br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge, !llvm.loop !1
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for.cond.for.end_crit_edge: ; preds = %for.body
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br label %for.end
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for.end: ; preds = %for.cond.for.end_crit_edge, %entry
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ret void
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}
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!1 = distinct !{!1}
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; Make sure peeling works correctly when a value defined in a loop is used
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; in later code - we need to correctly plumb the phi depending on which
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; iteration is actually used.
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define i32 @output(ptr %p, i32 %k) #0 {
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; CHECK-LABEL: define i32 @output(
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; CHECK-SAME: ptr [[P:%.*]], i32 [[K:%.*]]) {
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[CMP3:%.*]] = icmp sgt i32 [[K]], 0
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; CHECK-NEXT: br i1 [[CMP3]], label [[FOR_BODY_PEEL:%.*]], label [[FOR_END:%.*]]
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; CHECK: for.body.peel:
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; CHECK-NEXT: store i32 0, ptr [[P]], align 4
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; CHECK-NEXT: [[CMP_PEEL_NOT:%.*]] = icmp eq i32 [[K]], 1
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; CHECK-NEXT: br i1 [[CMP_PEEL_NOT]], label [[FOR_END]], label [[FOR_BODY_PEEL2:%.*]]
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; CHECK: for.body.peel2:
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; CHECK-NEXT: [[INCDEC_PTR_PEEL:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 4
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; CHECK-NEXT: store i32 1, ptr [[INCDEC_PTR_PEEL]], align 4
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; CHECK-NEXT: [[CMP_PEEL5:%.*]] = icmp sgt i32 [[K]], 2
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; CHECK-NEXT: br i1 [[CMP_PEEL5]], label [[FOR_BODY_PEEL7:%.*]], label [[FOR_END]]
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; CHECK: for.body.peel7:
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; CHECK-NEXT: [[INCDEC_PTR_PEEL3:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 8
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; CHECK-NEXT: [[INCDEC_PTR_PEEL8:%.*]] = getelementptr inbounds i8, ptr [[P]], i64 12
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; CHECK-NEXT: store i32 2, ptr [[INCDEC_PTR_PEEL3]], align 4
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; CHECK-NEXT: [[CMP_PEEL10_NOT:%.*]] = icmp eq i32 [[K]], 3
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; CHECK-NEXT: br i1 [[CMP_PEEL10_NOT]], label [[FOR_END]], label [[FOR_BODY:%.*]]
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; CHECK: for.body:
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; CHECK-NEXT: [[I_05:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ 3, [[FOR_BODY_PEEL7]] ]
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; CHECK-NEXT: [[P_ADDR_04:%.*]] = phi ptr [ [[INCDEC_PTR:%.*]], [[FOR_BODY]] ], [ [[INCDEC_PTR_PEEL8]], [[FOR_BODY_PEEL7]] ]
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; CHECK-NEXT: [[INCDEC_PTR]] = getelementptr inbounds i8, ptr [[P_ADDR_04]], i64 4
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; CHECK-NEXT: store i32 [[I_05]], ptr [[P_ADDR_04]], align 4
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; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I_05]], 1
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; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[INC]], [[K]]
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; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop [[LOOP3:![0-9]+]]
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; CHECK: for.end:
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; CHECK-NEXT: [[RET:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ 1, [[FOR_BODY_PEEL]] ], [ 2, [[FOR_BODY_PEEL2]] ], [ 3, [[FOR_BODY_PEEL7]] ], [ [[INC]], [[FOR_BODY]] ]
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; CHECK-NEXT: ret i32 [[RET]]
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;
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entry:
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%cmp3 = icmp slt i32 0, %k
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br i1 %cmp3, label %for.body.lr.ph, label %for.end
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for.body.lr.ph: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.lr.ph, %for.body
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%i.05 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
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%p.addr.04 = phi ptr [ %p, %for.body.lr.ph ], [ %incdec.ptr, %for.body ]
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%incdec.ptr = getelementptr inbounds i32, ptr %p.addr.04, i32 1
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store i32 %i.05, ptr %p.addr.04, align 4
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%inc = add nsw i32 %i.05, 1
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%cmp = icmp slt i32 %inc, %k
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br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge, !llvm.loop !2
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for.cond.for.end_crit_edge: ; preds = %for.body
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br label %for.end
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for.end: ; preds = %for.cond.for.end_crit_edge, %entry
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%ret = phi i32 [ 0, %entry], [ %inc, %for.cond.for.end_crit_edge ]
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ret i32 %ret
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}
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!2 = distinct !{!2}
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;.
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; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]}
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; CHECK: [[META1]] = !{!"llvm.loop.peeled.count", i32 3}
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; CHECK: [[META2]] = !{!"llvm.loop.unroll.disable"}
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; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META1]], [[META2]]}
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;.
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