caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
a78861fc55d18046989ff4d624a037e9181da170
clang-p2996/llvm/test/Transforms/LowerExpectIntrinsic/phi_unexpect.ll
Paul Kirth 294f3ce5dd Reapply "[llvm][IR] Extend BranchWeightMetadata to track provenance o… (#95281) 
…f weights" #95136

Reverts #95060, and relands #86609, with the unintended code generation
changes addressed.

This patch implements the changes to LLVM IR discussed in
https://discourse.llvm.org/t/rfc-update-branch-weights-metadata-to-allow-tracking-branch-weight-origins/75032

In this patch, we add an optional field to MD_prof meatdata nodes for
branch weights, which can be used to distinguish weights added from
llvm.expect* intrinsics from those added via other methods, e.g. from
profiles or inserted by the compiler.

One of the major motivations, is for use with MisExpect diagnostics,
which need to know if branch_weight metadata originates from an
llvm.expect intrinsic. Without that information, we end up checking
branch weights multiple times in the case if ThinLTO + SampleProfiling,
leading to some inaccuracy in how we report MisExpect related
diagnostics to users.

Since we change the format of MD_prof metadata in a fundamental way, we
need to update code handling branch weights in a number of places.

We also update the lang ref for branch weights to reflect the change.
2024-06-12 12:52:28 -07:00

240 lines
6.3 KiB
LLVM
Raw Blame History

; RUN: opt -S -passes='function(lower-expect),strip-dead-prototypes' -likely-branch-weight=2147483647 -unlikely-branch-weight=1 < %s | FileCheck %s
; The C case
; if (__builtin_expect_with_probability(((a0 == 1) || (a1 == 1) || (a2 == 1)), 1, 0))
; For the above case, all 3 branches should be annotated
; which should be equivalent to if (__builtin_expect(((a0 == 1) || (a1 == 1) || (a2 == 1)), 0))
; The C case
; if (__builtin_expect_with_probability(((a0 == 1) || (a1 == 1) || (a2 == 1)), 1, 1))
; For the above case, we do not have enough information, so only the last branch could be annotated
; which should be equivalent to if (__builtin_expect(((a0 == 1) || (a1 == 1) || (a2 == 1)), 1))
declare void @foo()
declare i64 @llvm.expect.i64(i64, i64) nounwind readnone
declare i64 @llvm.expect.with.probability.i64(i64, i64, double) nounwind readnone
; CHECK-LABEL: @test1_expect_1(
; CHECK: block0:
; CHECK-NOT: prof
; CHECK: block1:
; CHECK-NOT: prof
; CHECK: block3:
; CHECK: br i1 %tobool, label %block4, label %block5, !prof !0
define void @test1_expect_1(i8 %a0, i8 %a1, i8 %a2) {
block0:
%c0 = icmp eq i8 %a0, 1
br i1 %c0, label %block3, label %block1
block1:
%c1 = icmp eq i8 %a1, 1
br i1 %c1, label %block3, label %block2
block2:
%c2 = icmp eq i8 %a2, 1
br label %block3
block3:
%cond0 = phi i1 [ true, %block0 ], [ true, %block1 ], [ %c2, %block2 ]
%cond1 = zext i1 %cond0 to i32
%cond2 = sext i32 %cond1 to i64
%expval = call i64 @llvm.expect.i64(i64 %cond2, i64 1)
%tobool = icmp ne i64 %expval, 0
br i1 %tobool, label %block4, label %block5
block4:
call void @foo()
br label %block5
block5:
ret void
}
; should have exactly the same behavior as test1
; CHECK-LABEL: @test2_expect_with_prob_1_1(
; CHECK: block0:
; CHECK-NOT: prof
; CHECK: block1:
; CHECK-NOT: prof
; CHECK: block3:
; CHECK: br i1 %tobool, label %block4, label %block5, !prof !0
define void @test2_expect_with_prob_1_1(i8 %a0, i8 %a1, i8 %a2) {
block0:
%c0 = icmp eq i8 %a0, 1
br i1 %c0, label %block3, label %block1
block1:
%c1 = icmp eq i8 %a1, 1
br i1 %c1, label %block3, label %block2
block2:
%c2 = icmp eq i8 %a2, 1
br label %block3
block3:
%cond0 = phi i1 [ true, %block0 ], [ true, %block1 ], [ %c2, %block2 ]
%cond1 = zext i1 %cond0 to i32
%cond2 = sext i32 %cond1 to i64
%expval = call i64 @llvm.expect.with.probability.i64(i64 %cond2, i64 1, double 1.0)
%tobool = icmp ne i64 %expval, 0
br i1 %tobool, label %block4, label %block5
block4:
call void @foo()
br label %block5
block5:
ret void
}
; should have exactly the same behavior as test1
; CHECK-LABEL: @test3_expect_with_prob_0_0(
; CHECK: block0:
; CHECK-NOT: prof
; CHECK: block1:
; CHECK-NOT: prof
; CHECK: block3:
; CHECK: br i1 %tobool, label %block4, label %block5, !prof !0
define void @test3_expect_with_prob_0_0(i8 %a0, i8 %a1, i8 %a2) {
block0:
%c0 = icmp eq i8 %a0, 1
br i1 %c0, label %block3, label %block1
block1:
%c1 = icmp eq i8 %a1, 1
br i1 %c1, label %block3, label %block2
block2:
%c2 = icmp eq i8 %a2, 1
br label %block3
block3:
%cond0 = phi i1 [ true, %block0 ], [ true, %block1 ], [ %c2, %block2 ]
%cond1 = zext i1 %cond0 to i32
%cond2 = sext i32 %cond1 to i64
%expval = call i64 @llvm.expect.with.probability.i64(i64 %cond2, i64 0, double 0.0)
%tobool = icmp ne i64 %expval, 0
br i1 %tobool, label %block4, label %block5
block4:
call void @foo()
br label %block5
block5:
ret void
}
; CHECK-LABEL: @test4_expect_0(
; CHECK: block0:
; CHECK: br i1 %c0, label %block3, label %block1, !prof !1
; CHECK: block1:
; CHECK: br i1 %c1, label %block3, label %block2, !prof !1
; CHECK: block3:
; CHECK: br i1 %tobool, label %block4, label %block5, !prof !1
define void @test4_expect_0(i8 %a0, i8 %a1, i8 %a2) {
block0:
%c0 = icmp eq i8 %a0, 1
br i1 %c0, label %block3, label %block1
block1:
%c1 = icmp eq i8 %a1, 1
br i1 %c1, label %block3, label %block2
block2:
%c2 = icmp eq i8 %a2, 1
br label %block3
block3:
%cond0 = phi i1 [ true, %block0 ], [ true, %block1 ], [ %c2, %block2 ]
%cond1 = zext i1 %cond0 to i32
%cond2 = sext i32 %cond1 to i64
%expval = call i64 @llvm.expect.i64(i64 %cond2, i64 0)
%tobool = icmp ne i64 %expval, 0
br i1 %tobool, label %block4, label %block5
block4:
call void @foo()
br label %block5
block5:
ret void
}
; should have exactly the same behavior as test4
; CHECK-LABEL: @test5_expect_with_prob_1_0(
; CHECK: block0:
; CHECK: br i1 %c0, label %block3, label %block1, !prof !1
; CHECK: block1:
; CHECK: br i1 %c1, label %block3, label %block2, !prof !1
; CHECK: block3:
; CHECK: br i1 %tobool, label %block4, label %block5, !prof !1
define void @test5_expect_with_prob_1_0(i8 %a0, i8 %a1, i8 %a2) {
block0:
%c0 = icmp eq i8 %a0, 1
br i1 %c0, label %block3, label %block1
block1:
%c1 = icmp eq i8 %a1, 1
br i1 %c1, label %block3, label %block2
block2:
%c2 = icmp eq i8 %a2, 1
br label %block3
block3:
%cond0 = phi i1 [ true, %block0 ], [ true, %block1 ], [ %c2, %block2 ]
%cond1 = zext i1 %cond0 to i32
%cond2 = sext i32 %cond1 to i64
%expval = call i64 @llvm.expect.with.probability.i64(i64 %cond2, i64 1, double 0.0)
%tobool = icmp ne i64 %expval, 0
br i1 %tobool, label %block4, label %block5
block4:
call void @foo()
br label %block5
block5:
ret void
}
; should have exactly the same behavior as test4
; CHECK-LABEL: @test6_expect_with_prob_0_1(
; CHECK: block0:
; CHECK: br i1 %c0, label %block3, label %block1, !prof !1
; CHECK: block1:
; CHECK: br i1 %c1, label %block3, label %block2, !prof !1
; CHECK: block3:
; CHECK: br i1 %tobool, label %block4, label %block5, !prof !1
define void @test6_expect_with_prob_0_1(i8 %a0, i8 %a1, i8 %a2) {
block0:
%c0 = icmp eq i8 %a0, 1
br i1 %c0, label %block3, label %block1
block1:
%c1 = icmp eq i8 %a1, 1
br i1 %c1, label %block3, label %block2
block2:
%c2 = icmp eq i8 %a2, 1
br label %block3
block3:
%cond0 = phi i1 [ true, %block0 ], [ true, %block1 ], [ %c2, %block2 ]
%cond1 = zext i1 %cond0 to i32
%cond2 = sext i32 %cond1 to i64
%expval = call i64 @llvm.expect.with.probability.i64(i64 %cond2, i64 0, double 1.0)
%tobool = icmp ne i64 %expval, 0
br i1 %tobool, label %block4, label %block5
block4:
call void @foo()
br label %block5
block5:
ret void
}
; CHECK: !0 = !{!"branch_weights", !"expected", i32 2147483647, i32 1}
; CHECK: !1 = !{!"branch_weights", !"expected", i32 1, i32 2147483647}
Reference in New Issue View Git Blame Copy Permalink