371fcb720e
That transformation is lossy, as discussed in https://github.com/llvm/llvm-project/issues/53853 and https://github.com/rust-lang/rust/issues/85133#issuecomment-904185574 This is an alternative to D119839, which would add a limited IPSCCP into SimplifyCFG. Unlike lowering switch to lookup, we still want this transformation to happen relatively early, but after giving a chance for the things like CVP to do their thing. It seems like deferring it just until the IPSCCP is enough for the tests at hand, but perhaps we need to be more aggressive and disable it until CVP. Fixes https://github.com/llvm/llvm-project/issues/53853 Refs. https://github.com/rust-lang/rust/issues/85133 Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D119854
124 lines
4.2 KiB
LLVM
124 lines
4.2 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -forward-switch-cond=false -switch-range-to-icmp -S | FileCheck %s --check-prefix=NO_FWD
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; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -forward-switch-cond=true -switch-range-to-icmp -S | FileCheck %s --check-prefix=FWD
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; RUN: opt < %s -passes='simplifycfg<no-forward-switch-cond;switch-range-to-icmp>' -S | FileCheck %s --check-prefix=NO_FWD
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; RUN: opt < %s -passes='simplifycfg<forward-switch-cond;switch-range-to-icmp>' -S | FileCheck %s --check-prefix=FWD
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; PR10131
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
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target triple = "i386-pc-linux-gnu"
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define i32 @t(i32 %m) nounwind readnone {
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; NO_FWD-LABEL: @t(
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; NO_FWD-NEXT: entry:
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; NO_FWD-NEXT: switch i32 [[M:%.*]], label [[SW_BB4:%.*]] [
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; NO_FWD-NEXT: i32 0, label [[RETURN:%.*]]
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; NO_FWD-NEXT: i32 1, label [[SW_BB1:%.*]]
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; NO_FWD-NEXT: i32 2, label [[SW_BB2:%.*]]
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; NO_FWD-NEXT: i32 3, label [[SW_BB3:%.*]]
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; NO_FWD-NEXT: ]
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; NO_FWD: sw.bb1:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: sw.bb2:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: sw.bb3:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: sw.bb4:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: return:
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; NO_FWD-NEXT: [[RETVAL_0:%.*]] = phi i32 [ 4, [[SW_BB4]] ], [ 3, [[SW_BB3]] ], [ 2, [[SW_BB2]] ], [ 1, [[SW_BB1]] ], [ 0, [[ENTRY:%.*]] ]
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; NO_FWD-NEXT: ret i32 [[RETVAL_0]]
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;
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; FWD-LABEL: @t(
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; FWD-NEXT: entry:
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; FWD-NEXT: [[SWITCH:%.*]] = icmp ult i32 [[M:%.*]], 4
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; FWD-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[SWITCH]], i32 [[M]], i32 4
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; FWD-NEXT: ret i32 [[SPEC_SELECT]]
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;
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entry:
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switch i32 %m, label %sw.bb4 [
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i32 0, label %sw.bb0
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i32 1, label %sw.bb1
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i32 2, label %sw.bb2
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i32 3, label %sw.bb3
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]
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sw.bb0: ; preds = %entry
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br label %return
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sw.bb1: ; preds = %entry
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br label %return
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sw.bb2: ; preds = %entry
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br label %return
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sw.bb3: ; preds = %entry
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br label %return
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sw.bb4: ; preds = %entry
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br label %return
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return: ; preds = %entry, %sw.bb4, %sw.bb3, %sw.bb2, %sw.bb1
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%retval.0 = phi i32 [ 4, %sw.bb4 ], [ 3, %sw.bb3 ], [ 2, %sw.bb2 ], [ 1, %sw.bb1 ], [ 0, %sw.bb0 ]
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ret i32 %retval.0
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}
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; If 1 incoming phi value is a case constant of a switch, convert it to the switch condition:
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; https://bugs.llvm.org/show_bug.cgi?id=34471
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; This then subsequently should allow squashing of the other trivial case blocks.
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define i32 @PR34471(i32 %x) {
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; NO_FWD-LABEL: @PR34471(
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; NO_FWD-NEXT: entry:
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; NO_FWD-NEXT: switch i32 [[X:%.*]], label [[ELSE3:%.*]] [
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; NO_FWD-NEXT: i32 17, label [[RETURN:%.*]]
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; NO_FWD-NEXT: i32 19, label [[IF19:%.*]]
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; NO_FWD-NEXT: i32 42, label [[IF42:%.*]]
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; NO_FWD-NEXT: ]
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; NO_FWD: if19:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: if42:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: else3:
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; NO_FWD-NEXT: br label [[RETURN]]
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; NO_FWD: return:
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; NO_FWD-NEXT: [[R:%.*]] = phi i32 [ [[X]], [[IF19]] ], [ [[X]], [[IF42]] ], [ 0, [[ELSE3]] ], [ 17, [[ENTRY:%.*]] ]
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; NO_FWD-NEXT: ret i32 [[R]]
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;
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; FWD-LABEL: @PR34471(
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; FWD-NEXT: entry:
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; FWD-NEXT: switch i32 [[X:%.*]], label [[ELSE3:%.*]] [
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; FWD-NEXT: i32 17, label [[RETURN:%.*]]
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; FWD-NEXT: i32 19, label [[RETURN]]
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; FWD-NEXT: i32 42, label [[RETURN]]
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; FWD-NEXT: ]
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; FWD: else3:
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; FWD-NEXT: br label [[RETURN]]
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; FWD: return:
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; FWD-NEXT: [[R:%.*]] = phi i32 [ 0, [[ELSE3]] ], [ [[X]], [[ENTRY:%.*]] ], [ [[X]], [[ENTRY]] ], [ [[X]], [[ENTRY]] ]
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; FWD-NEXT: ret i32 [[R]]
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;
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entry:
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switch i32 %x, label %else3 [
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i32 17, label %return
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i32 19, label %if19
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i32 42, label %if42
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]
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if19:
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br label %return
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if42:
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br label %return
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else3:
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br label %return
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return:
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%r = phi i32 [ %x, %if19 ], [ %x, %if42 ], [ 0, %else3 ], [ 17, %entry ]
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ret i32 %r
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}
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