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clang-p2996/llvm/test/Transforms/InstCombine/overflow.ll
Nikita Popov 1376301c87 [InstCombine] Canonicalize range test idiom 
InstCombine converts range tests of the form (X > C1 && X < C2) or
(X < C1 || X > C2) into checks of the form (X + C3 < C4) or
(X + C3 > C4). It is possible to express all range tests in either
of these forms (with different choices of constants), but currently
neither of them is considered canonical. We may have equivalent
range tests using either ult or ugt.

This proposes to canonicalize all range tests to use ult. An
alternative would be to canonicalize to either ult or ugt depending
on the specific constants involved -- e.g. in practice we currently
generate ult for && style ranges and ugt for || style ranges when
going through the insertRangeTest() helper. In fact, the "clamp like"
fold was relying on this, which is why I had to tweak it to not
assume whether inversion is needed based on just the predicate.

Proof: https://alive2.llvm.org/ce/z/_SP_rQ

Differential Revision: https://reviews.llvm.org/D113366
2021-11-08 21:15:46 +01:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -instcombine < %s | FileCheck %s
; <rdar://problem/8558713>
declare void @throwAnExceptionOrWhatever()
define i32 @test1(i32 %a, i32 %b) nounwind ssp {
; CHECK-LABEL: @test1(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SADD:%.*]] = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 [[B:%.*]], i32 [[A:%.*]])
; CHECK-NEXT: [[TMP0:%.*]] = extractvalue { i32, i1 } [[SADD]], 1
; CHECK-NEXT: br i1 [[TMP0]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: tail call void @throwAnExceptionOrWhatever() #[[ATTR2:[0-9]+]]
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[SADD_RESULT:%.*]] = extractvalue { i32, i1 } [[SADD]], 0
; CHECK-NEXT: ret i32 [[SADD_RESULT]]
;
entry:
%conv = sext i32 %a to i64
%conv2 = sext i32 %b to i64
%add = add nsw i64 %conv2, %conv
%add.off = add i64 %add, 2147483648
%0 = icmp ugt i64 %add.off, 4294967295
br i1 %0, label %if.then, label %if.end
if.then:
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
%conv9 = trunc i64 %add to i32
ret i32 %conv9
}
; This form should not be promoted for two reasons: 1) it is unprofitable to
; promote it since the add.off instruction has another use, and 2) it is unsafe
; because the add-with-off makes the high bits of the original add live.
define i32 @test2(i32 %a, i32 %b, i64* %P) nounwind ssp {
; CHECK-LABEL: @test2(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CONV:%.*]] = sext i32 [[A:%.*]] to i64
; CHECK-NEXT: [[CONV2:%.*]] = sext i32 [[B:%.*]] to i64
; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[CONV2]], [[CONV]]
; CHECK-NEXT: [[ADD_OFF:%.*]] = add nsw i64 [[ADD]], 2147483648
; CHECK-NEXT: store i64 [[ADD_OFF]], i64* [[P:%.*]], align 4
; CHECK-NEXT: [[TMP0:%.*]] = icmp ugt i64 [[ADD_OFF]], 4294967295
; CHECK-NEXT: br i1 [[TMP0]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: tail call void @throwAnExceptionOrWhatever() #[[ATTR2]]
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[CONV9:%.*]] = trunc i64 [[ADD]] to i32
; CHECK-NEXT: ret i32 [[CONV9]]
;
entry:
%conv = sext i32 %a to i64
%conv2 = sext i32 %b to i64
%add = add nsw i64 %conv2, %conv
%add.off = add i64 %add, 2147483648
store i64 %add.off, i64* %P
%0 = icmp ugt i64 %add.off, 4294967295
br i1 %0, label %if.then, label %if.end
if.then:
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
%conv9 = trunc i64 %add to i32
ret i32 %conv9
}
; PR8816
; This is illegal to transform because the high bits of the original add are
; live out.
define i64 @test3(i32 %a, i32 %b) nounwind ssp {
; CHECK-LABEL: @test3(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CONV:%.*]] = sext i32 [[A:%.*]] to i64
; CHECK-NEXT: [[CONV2:%.*]] = sext i32 [[B:%.*]] to i64
; CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[CONV2]], [[CONV]]
; CHECK-NEXT: [[TMP0:%.*]] = add nsw i64 [[ADD]], -2147483648
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i64 [[TMP0]], -4294967296
; CHECK-NEXT: br i1 [[TMP1]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: tail call void @throwAnExceptionOrWhatever() #[[ATTR2]]
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: ret i64 [[ADD]]
;
entry:
%conv = sext i32 %a to i64
%conv2 = sext i32 %b to i64
%add = add nsw i64 %conv2, %conv
%add.off = add i64 %add, 2147483648
%0 = icmp ugt i64 %add.off, 4294967295
br i1 %0, label %if.then, label %if.end
if.then:
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
ret i64 %add
}
; Should be able to form an i8 sadd computed in an i32.
define zeroext i8 @test4(i8 signext %a, i8 signext %b) nounwind ssp {
; CHECK-LABEL: @test4(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SADD:%.*]] = call { i8, i1 } @llvm.sadd.with.overflow.i8(i8 [[B:%.*]], i8 [[A:%.*]])
; CHECK-NEXT: [[CMP:%.*]] = extractvalue { i8, i1 } [[SADD]], 1
; CHECK-NEXT: br i1 [[CMP]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: tail call void @throwAnExceptionOrWhatever() #[[ATTR2]]
; CHECK-NEXT: unreachable
; CHECK: if.end:
; CHECK-NEXT: [[SADD_RESULT:%.*]] = extractvalue { i8, i1 } [[SADD]], 0
; CHECK-NEXT: ret i8 [[SADD_RESULT]]
;
entry:
%conv = sext i8 %a to i32
%conv2 = sext i8 %b to i32
%add = add nsw i32 %conv2, %conv
%add4 = add nsw i32 %add, 128
%cmp = icmp ugt i32 %add4, 255
br i1 %cmp, label %if.then, label %if.end
if.then:
tail call void @throwAnExceptionOrWhatever() nounwind
unreachable
if.end:
%conv7 = trunc i32 %add to i8
ret i8 %conv7
}
; PR11438
; This is @test1, but the operands are not sign-extended. Make sure
; we don't transform this case.
define i32 @test8(i64 %a, i64 %b) nounwind ssp {
; CHECK-LABEL: @test8(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[ADD:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[ADD]], -2147483648
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i64 [[TMP0]], -4294967296
; CHECK-NEXT: br i1 [[TMP1]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: tail call void @throwAnExceptionOrWhatever() #[[ATTR2]]
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[CONV9:%.*]] = trunc i64 [[ADD]] to i32
; CHECK-NEXT: ret i32 [[CONV9]]
;
entry:
%add = add i64 %a, %b
%add.off = add i64 %add, 2147483648
%0 = icmp ugt i64 %add.off, 4294967295
br i1 %0, label %if.then, label %if.end
if.then:
tail call void @throwAnExceptionOrWhatever() nounwind
br label %if.end
if.end:
%conv9 = trunc i64 %add to i32
ret i32 %conv9
}
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