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[Codegen, BasicBlockSections] Avoid cloning blocks which have their machine block address taken. #94296

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Merged
merged 1 commit into from
Jun 4, 2024
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[Codegen, BasicBlockSections] Avoid cloning blocks which have their machine block address taken. #94296

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10 changes: 10 additions & 0 deletions llvm/lib/CodeGen/BasicBlockPathCloning.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,16 @@ bool IsValidCloning(const MachineFunction &MF,
return false;
}
}
if (PathBB->isMachineBlockAddressTaken()) {
// Avoid cloning blocks which have their address taken since we can't
// rewire branches to those blocks as easily (e.g., branches within
// inline assembly).
WithColor::warning()
<< "block #" << BBID
<< " has its machine block address taken in function "
<< MF.getName() << "\n";
return false;
}
}

if (I != ClonePath.size() - 1 && !PathBB->empty() &&
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27 changes: 21 additions & 6 deletions llvm/test/CodeGen/X86/basic-block-sections-cloning-invalid.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,8 @@ declare void @effect(i32 zeroext)
; RUN: echo 'v1' > %t2
; RUN: echo 'f foo' >> %t2
; RUN: echo 'p 0 2 3' >> %t2
; RUN: echo 'p 0 1 3' >> %t2
; RUN: echo 'c 0 1.1 3.2 2.1 3.1 1' >> %t2
; RUN: echo 'p 0 1 2 3' >> %t2
; RUN: echo 'c 0 1.1 2.2 3.2 2.1 3.1 1' >> %t2
; RUN: llc < %s -mtriple=x86_64-pc-linux -O0 -function-sections -basic-block-sections=%t2 2> %t2.err | FileCheck %s --check-prefixes=PATH
; RUN: FileCheck %s --check-prefixes=WARN1 < %t2.err
; RUN: echo 'v1' > %t3
Expand All @@ -23,6 +23,14 @@ declare void @effect(i32 zeroext)
; RUN: echo 'c 0 100.1 1' >> %t3
; RUN: llc < %s -mtriple=x86_64-pc-linux -O0 -function-sections -basic-block-sections=%t3 2> %t3.err | FileCheck %s
; RUN: FileCheck %s --check-prefixes=WARN2 < %t3.err
; RUN: echo 'v1' > %t4
; RUN: echo 'f foo' >> %t4
; RUN: echo 'p 1 6' >> %t4
; RUN: echo 'c 0 1 6.1' >> %t4
; RUN: llc < %s -mtriple=x86_64-pc-linux -O0 -function-sections -basic-block-sections=%t4 2> %t4.err | FileCheck %s
; RUN: FileCheck %s --check-prefixes=WARN3 < %t4.err



define void @foo(i1 %a, i1 %b, i1 %c, i1 %d) {
b0:
Expand All @@ -31,23 +39,29 @@ b0:

b1: ; preds = %b0
call void @effect(i32 1)
br i1 %b, label %b2, label %b3
br i1 %b, label %b2, label %b6

b2: ; preds = %b1
call void @effect(i32 2)
br label %b3

b3: ; preds = %b0, %b1, %b2
b3: ; preds = %b0, %b2
call void @effect(i32 3)
br i1 %c, label %b4, label %b5

b4: ; preds = %b3
call void @effect(i32 4)
br i1 %d, label %b5, label %cold
callbr void asm sideeffect "je ${0:l}", "!i,~{dirflag},~{fpsr},~{flags}"()
to label %b5 [label %b6]

b5: ; preds = %b3, %b4
call void @effect(i32 5)
ret void

b6: ; preds = %b1, %b4
call void @effect(i32 6)
ret void

cold:
call void @effect(i32 6) ; preds = %b4
ret void
Expand All @@ -59,7 +73,7 @@ cold:

; CHECK: je .LBB0_3
; PATH: # %bb.7: # %b1
; PATH: # %bb.8: # %b3
; PATH: # %bb.8: # %b2
; PATH: jne .LBB0_4
; CHECK: # %bb.1: # %b1
; CHECK: jne foo.cold
Expand All @@ -69,4 +83,5 @@ cold:
;; Check the warnings
; WARN1: warning: block #2 is not a successor of block #0 in function foo
; WARN2: warning: no block with id 100 in function foo
; WARN3: warning: block #6 has its machine block address taken in function foo

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