Assertion failed: "Cannot split critical edge from IndirectBrInst" with constant expression in PHI

[efriedma-quic]

Bugzilla Link	11246
Version	unspecified
OS	All
Attachments	Testcase
CC	@atrick,@fhahn

Extended Description

Testcase attached; llc crashes with:

Assertion failed: (!isa(TI) && "Cannot split critical edge from IndirectBrInst"), function SplitCriticalEdge, file /Volumes/storage/llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp, line 175.

Not sure anyone is actually likely to hit this in practice, but it seems possible.

[fhahn]

This still crashes on current trunk.

Modernized version of the reproducer:

target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.7.2"

@f = external global i32
@g = external global i32
@h = global i8* blockaddress(@u, %foo)
@i = global i8* blockaddress(@u, %bar)

define i32 @u(i32 %x, i8* %y) nounwind uwtable ssp {
entry:
  %tobool = icmp eq i32 %x, 0
  br i1 %tobool, label %if.else, label %if.then

if.then:
  %call = tail call i32 (...) @t() nounwind
  indirectbr i8* %y, [label %foo, label %bar]

if.else:
  indirectbr i8* %y, [label %foo, label %bar]

foo:
  %x.addr.0 = phi i32 [ %call, %if.then ], [ trunc (i64 sdiv (i64 100, i64 sdiv (i64 sub (i64 ptrtoint (i32* @f to i64), i64 ptrtoint (i32* @g to i64)), i64 4)) to i32), %if.else ]
  ret i32 %x.addr.0

bar:
  ret i32 0
}

declare i32 @t(...)

[mikaelholmen]

mentioned in issue llvm/llvm-bugzilla-archive#49893

[nikic]

This is resolved by the removal of trapping constant expressions (and thus also the need to perform critical edge splitting here).