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llvm-project/llvm/test/Transforms/SimplifyCFG/SpeculativeExec.ll

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Make some intrinsics safe to speculatively execute. llvm-svn: 147036
2011-12-21 13:52:02 +08:00
; RUN: opt < %s -simplifycfg -phi-node-folding-threshold=2 -S | FileCheck %s
Speculatively execute a block when the the block is the then part of a triangle shape and it contains a single, side effect free, cheap instruction. The branch is eliminated by adding a select instruction. i.e. Turn BB: %t1 = icmp br i1 %t1, label %BB1, label %BB2 BB1: %t3 = add %t2, c br label BB2 BB2: => BB: %t1 = icmp %t4 = add %t2, c %t3 = select i1 %t1, %t2, %t3 llvm-svn: 52073
2008-06-07 16:52:29 +08:00
Make some intrinsics safe to speculatively execute. llvm-svn: 147036
2011-12-21 13:52:02 +08:00
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-unknown-linux-gnu"
define i32 @test1(i32 %a, i32 %b, i32 %c) nounwind {
; CHECK: @test1
Speculatively execute a block when the the block is the then part of a triangle shape and it contains a single, side effect free, cheap instruction. The branch is eliminated by adding a select instruction. i.e. Turn BB: %t1 = icmp br i1 %t1, label %BB1, label %BB2 BB1: %t3 = add %t2, c br label BB2 BB2: => BB: %t1 = icmp %t4 = add %t2, c %t3 = select i1 %t1, %t2, %t3 llvm-svn: 52073
2008-06-07 16:52:29 +08:00
entry:
%tmp1 = icmp eq i32 %b, 0
br i1 %tmp1, label %bb1, label %bb3
bb1: ; preds = %entry
%tmp2 = icmp sgt i32 %c, 1
br i1 %tmp2, label %bb2, label %bb3
Make some intrinsics safe to speculatively execute. llvm-svn: 147036
2011-12-21 13:52:02 +08:00
; CHECK: bb1:
; CHECK-NEXT: icmp sgt i32 %c, 1
Revert r56315. When the instruction to speculate is a load, this code can incorrectly move the load across a store. This never happens in practice today, but only because the current heuristics accidentally preclude it. llvm-svn: 147623
2012-01-06 06:54:35 +08:00
; CHECK-NEXT: add i32 %a, 1
Make some intrinsics safe to speculatively execute. llvm-svn: 147036
2011-12-21 13:52:02 +08:00
; CHECK-NEXT: select i1 %tmp2, i32 %tmp3, i32 %a
; CHECK-NEXT: br label %bb3
Speculatively execute a block when the the block is the then part of a triangle shape and it contains a single, side effect free, cheap instruction. The branch is eliminated by adding a select instruction. i.e. Turn BB: %t1 = icmp br i1 %t1, label %BB1, label %BB2 BB1: %t3 = add %t2, c br label BB2 BB2: => BB: %t1 = icmp %t4 = add %t2, c %t3 = select i1 %t1, %t2, %t3 llvm-svn: 52073
2008-06-07 16:52:29 +08:00
bb2: ; preds = bb1
%tmp3 = add i32 %a, 1
br label %bb3
bb3: ; preds = %bb2, %entry
%tmp4 = phi i32 [ %b, %entry ], [ %a, %bb1 ], [ %tmp3, %bb2 ]
%tmp5 = sub i32 %tmp4, 1
ret i32 %tmp5
}
Make some intrinsics safe to speculatively execute. llvm-svn: 147036
2011-12-21 13:52:02 +08:00
declare i8 @llvm.cttz.i8(i8, i1)
define i8 @test2(i8 %a) {
; CHECK: @test2
br i1 undef, label %bb_true, label %bb_false
bb_true:
%b = tail call i8 @llvm.cttz.i8(i8 %a, i1 false)
br label %join
bb_false:
br label %join
join:
%c = phi i8 [%b, %bb_true], [%a, %bb_false]
; CHECK: select
ret i8 %c
}
Address a large chunk of this FIXME by accumulating the cost for unfolded constant expressions rather than checking each one independently. llvm-svn: 173341
2013-01-24 20:05:17 +08:00
define i8* @test4(i1* %dummy, i8* %a, i8* %b) {
; Test that we don't speculate an arbitrarily large number of unfolded constant
; expressions.
; CHECK: @test4
entry:
%cond1 = load volatile i1* %dummy
br i1 %cond1, label %if, label %end
if:
%cond2 = load volatile i1* %dummy
br i1 %cond2, label %then, label %end
then:
br label %end
end:
%x1 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 1 to i8*), %then ]
%x2 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 2 to i8*), %then ]
%x3 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 3 to i8*), %then ]
%x4 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 4 to i8*), %then ]
%x5 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 5 to i8*), %then ]
%x6 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 6 to i8*), %then ]
%x7 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 7 to i8*), %then ]
%x8 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 8 to i8*), %then ]
%x9 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 9 to i8*), %then ]
%x10 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 10 to i8*), %then ]
; CHECK-NOT: select
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
; CHECK: phi i8*
ret i8* %x10
}