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.
204 lines
8.6 KiB
LLVM
204 lines
8.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128-ni:1"
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target triple = "wasm32-unknown-unknown"
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%struct.quux = type { i32 }
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%struct.blam = type <{ i32, %struct.quux }>
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declare void @foo()
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declare void @bar(ptr)
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declare i32 @baz()
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declare i32 @__gxx_wasm_personality_v0(...)
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; Function Attrs: noreturn
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declare void @llvm.wasm.rethrow() #0
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; Test that a PHI in catchswitch BB are excluded from combining into a non-PHI
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; instruction.
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define void @test0(i1 %c1) personality ptr @__gxx_wasm_personality_v0 {
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; CHECK-LABEL: @test0(
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; CHECK-NEXT: bb:
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; CHECK-NEXT: [[TMP0:%.*]] = alloca [[STRUCT_BLAM:%.*]], align 4
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; CHECK-NEXT: br i1 [[C1:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
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; CHECK: bb1:
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; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i32 4
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; CHECK-NEXT: invoke void @foo()
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; CHECK-NEXT: to label [[BB3:%.*]] unwind label [[BB4:%.*]]
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; CHECK: bb2:
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; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i32 4
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; CHECK-NEXT: invoke void @foo()
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; CHECK-NEXT: to label [[BB3]] unwind label [[BB4]]
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; CHECK: bb3:
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; CHECK-NEXT: unreachable
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; CHECK: bb4:
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; CHECK-NEXT: [[TMP3:%.*]] = phi ptr [ [[TMP1]], [[BB1]] ], [ [[TMP2]], [[BB2]] ]
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; CHECK-NEXT: [[TMP4:%.*]] = catchswitch within none [label %bb5] unwind label [[BB7:%.*]]
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; CHECK: bb5:
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; CHECK-NEXT: [[TMP5:%.*]] = catchpad within [[TMP4]] [ptr null]
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; CHECK-NEXT: invoke void @foo() [ "funclet"(token [[TMP5]]) ]
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; CHECK-NEXT: to label [[BB6:%.*]] unwind label [[BB7]]
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; CHECK: bb6:
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; CHECK-NEXT: unreachable
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; CHECK: bb7:
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; CHECK-NEXT: [[TMP6:%.*]] = cleanuppad within none []
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; CHECK-NEXT: call void @bar(ptr nonnull [[TMP3]]) [ "funclet"(token [[TMP6]]) ]
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; CHECK-NEXT: unreachable
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;
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bb:
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%tmp0 = alloca %struct.blam, align 4
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br i1 %c1, label %bb1, label %bb2
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bb1: ; preds = %bb
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%tmp1 = getelementptr inbounds %struct.blam, ptr %tmp0, i32 0, i32 1
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invoke void @foo()
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to label %bb3 unwind label %bb4
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bb2: ; preds = %bb
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%tmp2 = getelementptr inbounds %struct.blam, ptr %tmp0, i32 0, i32 1
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invoke void @foo()
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to label %bb3 unwind label %bb4
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bb3: ; preds = %bb2, %bb1
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unreachable
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bb4: ; preds = %bb2, %bb1
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; This PHI should not be combined into a non-PHI instruction, because
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; catchswitch BB cannot have any non-PHI instruction other than catchswitch
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; itself.
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%tmp3 = phi ptr [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
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%tmp4 = catchswitch within none [label %bb5] unwind label %bb7
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bb5: ; preds = %bb4
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%tmp5 = catchpad within %tmp4 [ptr null]
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invoke void @foo() [ "funclet"(token %tmp5) ]
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to label %bb6 unwind label %bb7
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bb6: ; preds = %bb5
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unreachable
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bb7: ; preds = %bb5, %bb4
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%tmp6 = cleanuppad within none []
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call void @bar(ptr %tmp3) [ "funclet"(token %tmp6) ]
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unreachable
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}
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; Test that slicing-up of illegal integer type PHI does not happen in catchswitch
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; BBs, which can't have any non-PHI instruction before the catchswitch.
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define void @test1() personality ptr @__gxx_wasm_personality_v0 {
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; CHECK-LABEL: @test1(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: invoke void @foo()
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; CHECK-NEXT: to label [[INVOKE_CONT:%.*]] unwind label [[CATCH_DISPATCH1:%.*]]
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; CHECK: invoke.cont:
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; CHECK-NEXT: [[CALL:%.*]] = invoke i32 @baz()
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; CHECK-NEXT: to label [[INVOKE_CONT1:%.*]] unwind label [[CATCH_DISPATCH:%.*]]
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; CHECK: invoke.cont1:
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; CHECK-NEXT: [[TOBOOL_NOT:%.*]] = icmp eq i32 [[CALL]], 0
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; CHECK-NEXT: br i1 [[TOBOOL_NOT]], label [[IF_END:%.*]], label [[IF_THEN:%.*]]
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; CHECK: if.then:
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; CHECK-NEXT: br label [[IF_END]]
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; CHECK: if.end:
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; CHECK-NEXT: [[AP_0:%.*]] = phi i8 [ 1, [[IF_THEN]] ], [ 0, [[INVOKE_CONT1]] ]
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; CHECK-NEXT: invoke void @foo()
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; CHECK-NEXT: to label [[INVOKE_CONT2:%.*]] unwind label [[CATCH_DISPATCH]]
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; CHECK: invoke.cont2:
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; CHECK-NEXT: br label [[TRY_CONT:%.*]]
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; CHECK: catch.dispatch:
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; CHECK-NEXT: [[AP_1:%.*]] = phi i8 [ [[AP_0]], [[IF_END]] ], [ 0, [[INVOKE_CONT]] ]
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; CHECK-NEXT: [[TMP0:%.*]] = catchswitch within none [label %catch.start] unwind label [[CATCH_DISPATCH1]]
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; CHECK: catch.start:
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; CHECK-NEXT: [[TMP1:%.*]] = catchpad within [[TMP0]] [ptr null]
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; CHECK-NEXT: br i1 false, label [[CATCH:%.*]], label [[RETHROW:%.*]]
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; CHECK: catch:
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; CHECK-NEXT: catchret from [[TMP1]] to label [[TRY_CONT]]
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; CHECK: rethrow:
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; CHECK-NEXT: invoke void @llvm.wasm.rethrow() #[[ATTR0:[0-9]+]] [ "funclet"(token [[TMP1]]) ]
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; CHECK-NEXT: to label [[UNREACHABLE:%.*]] unwind label [[CATCH_DISPATCH1]]
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; CHECK: catch.dispatch1:
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; CHECK-NEXT: [[AP_2:%.*]] = phi i8 [ [[AP_1]], [[CATCH_DISPATCH]] ], [ [[AP_1]], [[RETHROW]] ], [ 0, [[ENTRY:%.*]] ]
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; CHECK-NEXT: [[TMP2:%.*]] = catchswitch within none [label %catch.start1] unwind to caller
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; CHECK: catch.start1:
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; CHECK-NEXT: [[TMP3:%.*]] = catchpad within [[TMP2]] [ptr null]
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; CHECK-NEXT: [[TMP0:%.*]] = and i8 [[AP_2]], 1
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; CHECK-NEXT: [[TOBOOL1_NOT:%.*]] = icmp eq i8 [[TMP0]], 0
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; CHECK-NEXT: br i1 [[TOBOOL1_NOT]], label [[IF_END1:%.*]], label [[IF_THEN1:%.*]]
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; CHECK: if.then1:
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; CHECK-NEXT: br label [[IF_END1]]
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; CHECK: if.end1:
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; CHECK-NEXT: catchret from [[TMP3]] to label [[TRY_CONT]]
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; CHECK: try.cont:
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; CHECK-NEXT: ret void
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; CHECK: unreachable:
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; CHECK-NEXT: unreachable
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;
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entry:
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invoke void @foo()
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to label %invoke.cont unwind label %catch.dispatch1
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invoke.cont: ; preds = %entry
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%call = invoke i32 @baz()
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to label %invoke.cont1 unwind label %catch.dispatch
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invoke.cont1: ; preds = %invoke.cont
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%tobool = icmp ne i32 %call, 0
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br i1 %tobool, label %if.then, label %if.end
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if.then: ; preds = %invoke.cont1
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br label %if.end
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if.end: ; preds = %if.then, %invoke.cont1
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%ap.0 = phi i8 [ 1, %if.then ], [ 0, %invoke.cont1 ]
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invoke void @foo()
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to label %invoke.cont2 unwind label %catch.dispatch
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invoke.cont2: ; preds = %if.end
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br label %try.cont
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catch.dispatch: ; preds = %if.end, %invoke.cont
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; %ap.2 in catch.dispatch1 BB has an illegal integer type (i8) in the data
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; layout, and it is only used by trunc or trunc(lshr) operations. In this case
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; InstCombine will split this PHI in its predecessors, which include this
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; catch.dispatch BB. This splitting involves creating non-PHI instructions,
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; such as 'and' or 'icmp' in this BB, which is not valid for a catchswitch BB.
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; So if one of sliced-up PHI's predecessor is a catchswitch block, we don't
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; optimize that case and bail out. This BB should be preserved intact after
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; InstCombine and the pass shouldn't produce invalid code.
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%ap.1 = phi i8 [ %ap.0, %if.end ], [ 0, %invoke.cont ]
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%tmp0 = catchswitch within none [label %catch.start] unwind label %catch.dispatch1
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catch.start: ; preds = %catch.dispatch
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%tmp1 = catchpad within %tmp0 [ptr null]
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br i1 0, label %catch, label %rethrow
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catch: ; preds = %catch.start
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catchret from %tmp1 to label %try.cont
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rethrow: ; preds = %catch.start
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invoke void @llvm.wasm.rethrow() #0 [ "funclet"(token %tmp1) ]
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to label %unreachable unwind label %catch.dispatch1
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catch.dispatch1: ; preds = %rethrow, %catch.dispatch, %entry
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%ap.2 = phi i8 [ %ap.1, %catch.dispatch ], [ %ap.1, %rethrow ], [ 0, %entry ]
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%tmp2 = catchswitch within none [label %catch.start1] unwind to caller
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catch.start1: ; preds = %catch.dispatch1
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%tmp3 = catchpad within %tmp2 [ptr null]
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%tobool1 = trunc i8 %ap.2 to i1
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br i1 %tobool1, label %if.then1, label %if.end1
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if.then1: ; preds = %catch.start1
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br label %if.end1
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if.end1: ; preds = %if.then1, %catch.start1
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catchret from %tmp3 to label %try.cont
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try.cont: ; preds = %if.end1, %catch, %invoke.cont2
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ret void
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unreachable: ; preds = %rethrow
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unreachable
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}
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attributes #0 = { noreturn }
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