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570033ed62
We want to add a way to avoid merging identical calls so as to keep the separate debug-information for those calls. There is also an asan usecase where having this attribute would be beneficial to avoid alternative work-arounds. Here is the link to the feature request: https://bugs.llvm.org/show_bug.cgi?id=42783. `nomerge` is different from `noline`. `noinline` prevents function from inlining at callsites, but `nomerge` prevents multiple identical calls from being merged into one. This patch adds `nomerge` to disable the optimization in IR level. A followup patch will be needed to let backend understands `nomerge` and avoid tail merge at backend. Reviewed By: asbirlea, rnk Differential Revision: https://reviews.llvm.org/D78659
72 lines
1.5 KiB
LLVM
72 lines
1.5 KiB
LLVM
; RUN: opt < %s -O1 -S | FileCheck %s
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; The attribute nomerge prevents the 3 bar() calls from being sunk/hoisted into
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; one inside a function. Check that there are still 3 tail calls.
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; Test case for preventing sinking
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; CHECK-LABEL: define void @sink
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; CHECK: if.then:
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; CHECK-NEXT: tail call void @bar()
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; CHECK: if.then2:
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; CHECK-NEXT: tail call void @bar()
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; CHECK: if.end3:
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; CHECK-NEXT: tail call void @bar()
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define void @sink(i32 %i) {
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entry:
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switch i32 %i, label %if.end3 [
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i32 5, label %if.then
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i32 7, label %if.then2
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]
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if.then:
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tail call void @bar() #0
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br label %if.end3
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if.then2:
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tail call void @bar() #0
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br label %if.end3
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if.end3:
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tail call void @bar() #0
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ret void
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}
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; Test case for preventing hoisting
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; CHECK-LABEL: define void @hoist
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; CHECK: if.then:
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; CHECK-NEXT: tail call void @bar()
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; CHECK: if.then2:
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; CHECK-NEXT: tail call void @bar()
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; CHECK: if.end:
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; CHECK-NEXT: tail call void @bar()
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define void @hoist(i32 %i) {
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entry:
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%i.addr = alloca i32, align 4
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store i32 %i, i32* %i.addr, align 4
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%0 = load i32, i32* %i.addr, align 4
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%cmp = icmp eq i32 %0, 5
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br i1 %cmp, label %if.then, label %if.else
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if.then:
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tail call void @bar() #1
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unreachable
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if.else:
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%1 = load i32, i32* %i.addr, align 4
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%cmp1 = icmp eq i32 %i, 7
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br i1 %cmp1, label %if.then2, label %if.end
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if.then2:
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tail call void @bar() #1
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unreachable
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if.end:
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tail call void @bar() #1
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unreachable
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}
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declare void @bar()
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attributes #0 = { nomerge }
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attributes #1 = { noreturn nomerge }
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