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https://github.com/c64scene-ar/llvm-6502.git
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7765492a7a
Scan the body of the loop and find instructions that may trap. Use this information when deciding if it is safe to hoist or sink instructions. Notice that we can optimize the search of instructions that may throw in the case of nested loops. rdar://11518836 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163132 91177308-0d34-0410-b5e6-96231b3b80d8
93 lines
2.3 KiB
LLVM
93 lines
2.3 KiB
LLVM
; RUN: opt < %s -licm -S | FileCheck %s
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@X = global i32 0 ; <i32*> [#uses=1]
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declare void @foo()
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; This testcase tests for a problem where LICM hoists
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; potentially trapping instructions when they are not guaranteed to execute.
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define i32 @test1(i1 %c) {
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; CHECK: @test1
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%A = load i32* @X ; <i32> [#uses=2]
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br label %Loop
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Loop: ; preds = %LoopTail, %0
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call void @foo( )
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br i1 %c, label %LoopTail, label %IfUnEqual
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IfUnEqual: ; preds = %Loop
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; CHECK: IfUnEqual:
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; CHECK-NEXT: sdiv i32 4, %A
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%B1 = sdiv i32 4, %A ; <i32> [#uses=1]
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br label %LoopTail
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LoopTail: ; preds = %IfUnEqual, %Loop
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%B = phi i32 [ 0, %Loop ], [ %B1, %IfUnEqual ] ; <i32> [#uses=1]
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br i1 %c, label %Loop, label %Out
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Out: ; preds = %LoopTail
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%C = sub i32 %A, %B ; <i32> [#uses=1]
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ret i32 %C
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}
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declare void @foo2(i32) nounwind
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;; It is ok and desirable to hoist this potentially trapping instruction.
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define i32 @test2(i1 %c) {
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; CHECK: @test2
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; CHECK-NEXT: load i32* @X
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; CHECK-NEXT: %B = sdiv i32 4, %A
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%A = load i32* @X ; <i32> [#uses=2]
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br label %Loop
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Loop:
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;; Should have hoisted this div!
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%B = sdiv i32 4, %A ; <i32> [#uses=2]
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call void @foo2( i32 %B )
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br i1 %c, label %Loop, label %Out
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Out: ; preds = %Loop
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%C = sub i32 %A, %B ; <i32> [#uses=1]
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ret i32 %C
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}
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; This loop invariant instruction should be constant folded, not hoisted.
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define i32 @test3(i1 %c) {
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; CHECK: define i32 @test3
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; CHECK: call void @foo2(i32 6)
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%A = load i32* @X ; <i32> [#uses=2]
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br label %Loop
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Loop:
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%B = add i32 4, 2 ; <i32> [#uses=2]
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call void @foo2( i32 %B )
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br i1 %c, label %Loop, label %Out
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Out: ; preds = %Loop
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%C = sub i32 %A, %B ; <i32> [#uses=1]
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ret i32 %C
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}
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; CHECK: @test4
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; CHECK: call
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; CHECK: sdiv
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; CHECK: ret
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define i32 @test4(i32 %x, i32 %y) nounwind uwtable ssp {
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entry:
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i.02 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%n.01 = phi i32 [ 0, %entry ], [ %add, %for.body ]
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call void @foo_may_call_exit(i32 0)
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%div = sdiv i32 %x, %y
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%add = add nsw i32 %n.01, %div
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%inc = add nsw i32 %i.02, 1
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%cmp = icmp slt i32 %inc, 10000
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body
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%n.0.lcssa = phi i32 [ %add, %for.body ]
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ret i32 %n.0.lcssa
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}
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declare void @foo_may_call_exit(i32)
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