661cc71a1c
Retry of 330619a3a6 that includes a clang test update.
Original commit message:
If we run passes before lowering llvm.expect intrinsics to metadata,
then those passes have no way to act on the hints provided by llvm.expect.
SimplifyCFG is the known offender, and we made it smarter about profile
metadata in D98898 <https://reviews.llvm.org/D98898>.
In the motivating example from https://llvm.org/PR49336 , this means we
were ignoring the recommended method for a programmer to tell the compiler
that a compare+branch is expensive. This change appears to solve that case -
the metadata survives to the backend, the compare order is as expected in IR,
and the backend does not do anything to reverse it.
We make the same change to the old pass manager to keep things synchronized.
Differential Revision: https://reviews.llvm.org/D100213
55 lines
1.7 KiB
LLVM
55 lines
1.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
|
|
; RUN: opt -O2 -S < %s | FileCheck %s
|
|
|
|
; Given an "expect" on a compare, we should not combine
|
|
; that compare with other instructions in a way that the
|
|
; backend can't undo. Expect lowering becomes metadata,
|
|
; and passes like SimplifyCFG should respect that.
|
|
|
|
define void @PR49336(i32 %delta, i32 %tag_type, i8* %ip) {
|
|
; CHECK-LABEL: @PR49336(
|
|
; CHECK-NEXT: entry:
|
|
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[DELTA:%.*]], 0
|
|
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END3:%.*]], !prof !0
|
|
; CHECK: if.then:
|
|
; CHECK-NEXT: [[CMP1_NOT:%.*]] = icmp eq i32 [[TAG_TYPE:%.*]], 0
|
|
; CHECK-NEXT: br i1 [[CMP1_NOT]], label [[IF_END3]], label [[IF_THEN2:%.*]]
|
|
; CHECK: if.then2:
|
|
; CHECK-NEXT: store i8 42, i8* [[IP:%.*]], align 1
|
|
; CHECK-NEXT: br label [[IF_END3]]
|
|
; CHECK: if.end3:
|
|
; CHECK-NEXT: ret void
|
|
;
|
|
entry:
|
|
%delta.addr = alloca i32, align 4
|
|
%tag_type.addr = alloca i32, align 4
|
|
%ip.addr = alloca i8*, align 8
|
|
store i32 %delta, i32* %delta.addr, align 4
|
|
store i32 %tag_type, i32* %tag_type.addr, align 4
|
|
store i8* %ip, i8** %ip.addr, align 8
|
|
%0 = load i32, i32* %delta.addr, align 4
|
|
%cmp = icmp slt i32 %0, 0
|
|
%conv = zext i1 %cmp to i64
|
|
%expval = call i64 @llvm.expect.i64(i64 %conv, i64 0)
|
|
%tobool = icmp ne i64 %expval, 0
|
|
br i1 %tobool, label %if.then, label %if.end3
|
|
|
|
if.then:
|
|
%1 = load i32, i32* %tag_type.addr, align 4
|
|
%cmp1 = icmp ne i32 %1, 0
|
|
br i1 %cmp1, label %if.then2, label %if.end
|
|
|
|
if.then2:
|
|
%2 = load i8*, i8** %ip.addr, align 8
|
|
store i8 42, i8* %2, align 1
|
|
br label %if.end
|
|
|
|
if.end:
|
|
br label %if.end3
|
|
|
|
if.end3:
|
|
ret void
|
|
}
|
|
|
|
declare i64 @llvm.expect.i64(i64, i64)
|