llvm/test/Transforms/InstCombine/minmax-fold.ll
Sanjay Patel fea0530bd5 [InstCombine] canonicalize min/max constant to select's false value
This is a first step towards canonicalization and improved folding/codegen
for integer min/max as discussed here:
http://lists.llvm.org/pipermail/llvm-dev/2016-November/106868.html

Here, we're just matching the simplest min/max patterns and adjusting the
icmp predicate while swapping the select operands.

I've included FIXME tests in test/Transforms/InstCombine/select_meta.ll
so it's easier to see how this might be extended (corresponds to the TODO
comment in the code). That's also why I'm using matchSelectPattern()
rather than a simpler check; once the backend is patched, we can just 
remove some of the restrictions to allow the obfuscated min/max patterns
in the FIXME tests to be matched.

Differential Revision: https://reviews.llvm.org/D26525


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287585 91177308-0d34-0410-b5e6-96231b3b80d8
2016-11-21 22:04:14 +00:00

342 lines
11 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -instcombine < %s | FileCheck %s
; This is the canonical form for a type-changing min/max.
define i64 @t1(i32 %a) {
; CHECK-LABEL: @t1(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %a, 5
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 %a, i32 5
; CHECK-NEXT: [[TMP3:%.*]] = sext i32 [[TMP2]] to i64
; CHECK-NEXT: ret i64 [[TMP3]]
;
%1 = icmp slt i32 %a, 5
%2 = select i1 %1, i32 %a, i32 5
%3 = sext i32 %2 to i64
ret i64 %3
}
; Check this is converted into canonical form, as above.
define i64 @t2(i32 %a) {
; CHECK-LABEL: @t2(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %a, 5
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 %a, i32 5
; CHECK-NEXT: [[TMP3:%.*]] = sext i32 [[TMP2]] to i64
; CHECK-NEXT: ret i64 [[TMP3]]
;
%1 = icmp slt i32 %a, 5
%2 = sext i32 %a to i64
%3 = select i1 %1, i64 %2, i64 5
ret i64 %3
}
; Same as @t2, with flipped operands and zext instead of sext.
define i64 @t3(i32 %a) {
; CHECK-LABEL: @t3(
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 %a, 5
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 %a, i32 5
; CHECK-NEXT: [[TMP3:%.*]] = zext i32 [[TMP2]] to i64
; CHECK-NEXT: ret i64 [[TMP3]]
;
%1 = icmp ult i32 %a, 5
%2 = zext i32 %a to i64
%3 = select i1 %1, i64 5, i64 %2
ret i64 %3
}
; Same again, with trunc.
define i32 @t4(i64 %a) {
; CHECK-LABEL: @t4(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i64 %a, 5
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i64 %a, i64 5
; CHECK-NEXT: [[TMP3:%.*]] = trunc i64 [[TMP2]] to i32
; CHECK-NEXT: ret i32 [[TMP3]]
;
%1 = icmp slt i64 %a, 5
%2 = trunc i64 %a to i32
%3 = select i1 %1, i32 %2, i32 5
ret i32 %3
}
; Same as @t3, but with mismatched signedness between icmp and zext.
; InstCombine should leave this alone.
define i64 @t5(i32 %a) {
; CHECK-LABEL: @t5(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %a, 5
; CHECK-NEXT: [[TMP2:%.*]] = zext i32 %a to i64
; CHECK-NEXT: [[TMP3:%.*]] = select i1 [[TMP1]], i64 5, i64 [[TMP2]]
; CHECK-NEXT: ret i64 [[TMP3]]
;
%1 = icmp slt i32 %a, 5
%2 = zext i32 %a to i64
%3 = select i1 %1, i64 5, i64 %2
ret i64 %3
}
define float @t6(i32 %a) {
; CHECK-LABEL: @t6(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %a, 0
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 %a, i32 0
; CHECK-NEXT: [[TMP3:%.*]] = sitofp i32 [[TMP2]] to float
; CHECK-NEXT: ret float [[TMP3]]
;
%1 = icmp slt i32 %a, 0
%2 = select i1 %1, i32 %a, i32 0
%3 = sitofp i32 %2 to float
ret float %3
}
define i16 @t7(i32 %a) {
; CHECK-LABEL: @t7(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %a, -32768
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i32 %a, i32 -32768
; CHECK-NEXT: [[TMP3:%.*]] = trunc i32 [[TMP2]] to i16
; CHECK-NEXT: ret i16 [[TMP3]]
;
%1 = icmp slt i32 %a, -32768
%2 = trunc i32 %a to i16
%3 = select i1 %1, i16 %2, i16 -32768
ret i16 %3
}
; Just check for no infinite loop. InstSimplify liked to
; "simplify" -32767 by removing all the sign bits,
; which led to a canonicalization fight between different
; parts of instcombine.
define i32 @t8(i64 %a, i32 %b) {
; CHECK-LABEL: @t8(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i64 %a, -32767
; CHECK-NEXT: [[TMP2:%.*]] = select i1 [[TMP1]], i64 %a, i64 -32767
; CHECK-NEXT: [[TMP3:%.*]] = trunc i64 [[TMP2]] to i32
; CHECK-NEXT: [[TMP4:%.*]] = icmp slt i32 %b, 42
; CHECK-NEXT: [[TMP5:%.*]] = select i1 [[TMP4]], i32 42, i32 [[TMP3]]
; CHECK-NEXT: [[TMP6:%.*]] = icmp ne i32 [[TMP5]], %b
; CHECK-NEXT: [[TMP7:%.*]] = zext i1 [[TMP6]] to i32
; CHECK-NEXT: ret i32 [[TMP7]]
;
%1 = icmp slt i64 %a, -32767
%2 = select i1 %1, i64 %a, i64 -32767
%3 = trunc i64 %2 to i32
%4 = icmp slt i32 %b, 42
%5 = select i1 %4, i32 42, i32 %3
%6 = icmp ne i32 %5, %b
%7 = zext i1 %6 to i32
ret i32 %7
}
; Ensure this doesn't get converted to a min/max.
define i64 @t9(i32 %a) {
; CHECK-LABEL: @t9(
; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 %a, -1
; CHECK-NEXT: [[TMP2:%.*]] = sext i32 %a to i64
; CHECK-NEXT: [[TMP3:%.*]] = select i1 [[TMP1]], i64 [[TMP2]], i64 4294967295
; CHECK-NEXT: ret i64 [[TMP3]]
;
%1 = icmp sgt i32 %a, -1
%2 = sext i32 %a to i64
%3 = select i1 %1, i64 %2, i64 4294967295
ret i64 %3
}
; Reuse the first 2 bitcasts as the select operands.
define <4 x i32> @bitcasts_fcmp_1(<2 x i64> %a, <2 x i64> %b) {
; CHECK-LABEL: @bitcasts_fcmp_1(
; CHECK-NEXT: [[T0:%.*]] = bitcast <2 x i64> %a to <4 x float>
; CHECK-NEXT: [[T1:%.*]] = bitcast <2 x i64> %b to <4 x float>
; CHECK-NEXT: [[T2:%.*]] = fcmp olt <4 x float> [[T1]], [[T0]]
; CHECK-NEXT: [[TMP1:%.*]] = select <4 x i1> [[T2]], <4 x float> [[T0]], <4 x float> [[T1]]
; CHECK-NEXT: [[T5:%.*]] = bitcast <4 x float> [[TMP1]] to <4 x i32>
; CHECK-NEXT: ret <4 x i32> [[T5]]
;
%t0 = bitcast <2 x i64> %a to <4 x float>
%t1 = bitcast <2 x i64> %b to <4 x float>
%t2 = fcmp olt <4 x float> %t1, %t0
%t3 = bitcast <2 x i64> %a to <4 x i32>
%t4 = bitcast <2 x i64> %b to <4 x i32>
%t5 = select <4 x i1> %t2, <4 x i32> %t3, <4 x i32> %t4
ret <4 x i32> %t5
}
; Switch cmp operand order.
define <4 x i32> @bitcasts_fcmp_2(<2 x i64> %a, <2 x i64> %b) {
; CHECK-LABEL: @bitcasts_fcmp_2(
; CHECK-NEXT: [[T0:%.*]] = bitcast <2 x i64> %a to <4 x float>
; CHECK-NEXT: [[T1:%.*]] = bitcast <2 x i64> %b to <4 x float>
; CHECK-NEXT: [[T2:%.*]] = fcmp olt <4 x float> [[T0]], [[T1]]
; CHECK-NEXT: [[TMP1:%.*]] = select <4 x i1> [[T2]], <4 x float> [[T0]], <4 x float> [[T1]]
; CHECK-NEXT: [[T5:%.*]] = bitcast <4 x float> [[TMP1]] to <4 x i32>
; CHECK-NEXT: ret <4 x i32> [[T5]]
;
%t0 = bitcast <2 x i64> %a to <4 x float>
%t1 = bitcast <2 x i64> %b to <4 x float>
%t2 = fcmp olt <4 x float> %t0, %t1
%t3 = bitcast <2 x i64> %a to <4 x i32>
%t4 = bitcast <2 x i64> %b to <4 x i32>
%t5 = select <4 x i1> %t2, <4 x i32> %t3, <4 x i32> %t4
ret <4 x i32> %t5
}
; Integer cmp should have the same transforms.
define <4 x float> @bitcasts_icmp(<2 x i64> %a, <2 x i64> %b) {
; CHECK-LABEL: @bitcasts_icmp(
; CHECK-NEXT: [[T0:%.*]] = bitcast <2 x i64> %a to <4 x i32>
; CHECK-NEXT: [[T1:%.*]] = bitcast <2 x i64> %b to <4 x i32>
; CHECK-NEXT: [[T2:%.*]] = icmp slt <4 x i32> [[T1]], [[T0]]
; CHECK-NEXT: [[TMP1:%.*]] = select <4 x i1> [[T2]], <4 x i32> [[T0]], <4 x i32> [[T1]]
; CHECK-NEXT: [[T5:%.*]] = bitcast <4 x i32> [[TMP1]] to <4 x float>
; CHECK-NEXT: ret <4 x float> [[T5]]
;
%t0 = bitcast <2 x i64> %a to <4 x i32>
%t1 = bitcast <2 x i64> %b to <4 x i32>
%t2 = icmp slt <4 x i32> %t1, %t0
%t3 = bitcast <2 x i64> %a to <4 x float>
%t4 = bitcast <2 x i64> %b to <4 x float>
%t5 = select <4 x i1> %t2, <4 x float> %t3, <4 x float> %t4
ret <4 x float> %t5
}
; SMIN(SMIN(X, 11), 92) -> SMIN(X, 11)
define i32 @test68(i32 %x) {
; CHECK-LABEL: @test68(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %x, 11
; CHECK-NEXT: [[COND:%.*]] = select i1 [[TMP1]], i32 %x, i32 11
; CHECK-NEXT: ret i32 [[COND]]
;
%cmp = icmp slt i32 11, %x
%cond = select i1 %cmp, i32 11, i32 %x
%cmp3 = icmp slt i32 92, %cond
%retval = select i1 %cmp3, i32 92, i32 %cond
ret i32 %retval
}
define <2 x i32> @test68vec(<2 x i32> %x) {
; CHECK-LABEL: @test68vec(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <2 x i32> %x, <i32 11, i32 11>
; CHECK-NEXT: [[COND:%.*]] = select <2 x i1> [[TMP1]], <2 x i32> %x, <2 x i32> <i32 11, i32 11>
; CHECK-NEXT: ret <2 x i32> [[COND]]
;
%cmp = icmp slt <2 x i32> <i32 11, i32 11>, %x
%cond = select <2 x i1> %cmp, <2 x i32> <i32 11, i32 11>, <2 x i32> %x
%cmp3 = icmp slt <2 x i32> <i32 92, i32 92>, %cond
%retval = select <2 x i1> %cmp3, <2 x i32> <i32 92, i32 92>, <2 x i32> %cond
ret <2 x i32> %retval
}
; MIN(MIN(X, 24), 83) -> MIN(X, 24)
define i32 @test69(i32 %x) {
; CHECK-LABEL: @test69(
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 %x, 24
; CHECK-NEXT: [[COND:%.*]] = select i1 [[TMP1]], i32 %x, i32 24
; CHECK-NEXT: ret i32 [[COND]]
;
%cmp = icmp ult i32 24, %x
%cond = select i1 %cmp, i32 24, i32 %x
%cmp3 = icmp ult i32 83, %cond
%retval = select i1 %cmp3, i32 83, i32 %cond
ret i32 %retval
}
; SMAX(SMAX(X, 75), 36) -> SMAX(X, 75)
define i32 @test70(i32 %x) {
; CHECK-LABEL: @test70(
; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 %x, 75
; CHECK-NEXT: [[COND:%.*]] = select i1 [[TMP1]], i32 %x, i32 75
; CHECK-NEXT: ret i32 [[COND]]
;
%cmp = icmp slt i32 %x, 75
%cond = select i1 %cmp, i32 75, i32 %x
%cmp3 = icmp slt i32 %cond, 36
%retval = select i1 %cmp3, i32 36, i32 %cond
ret i32 %retval
}
; MAX(MAX(X, 68), 47) -> MAX(X, 68)
define i32 @test71(i32 %x) {
; CHECK-LABEL: @test71(
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 %x, 68
; CHECK-NEXT: [[COND:%.*]] = select i1 [[TMP1]], i32 %x, i32 68
; CHECK-NEXT: ret i32 [[COND]]
;
%cmp = icmp ult i32 %x, 68
%cond = select i1 %cmp, i32 68, i32 %x
%cmp3 = icmp ult i32 %cond, 47
%retval = select i1 %cmp3, i32 47, i32 %cond
ret i32 %retval
}
; SMIN(SMIN(X, 92), 11) -> SMIN(X, 11)
define i32 @test72(i32 %x) {
; CHECK-LABEL: @test72(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 %x, 11
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[TMP1]], i32 %x, i32 11
; CHECK-NEXT: ret i32 [[RETVAL]]
;
%cmp = icmp sgt i32 %x, 92
%cond = select i1 %cmp, i32 92, i32 %x
%cmp3 = icmp sgt i32 %cond, 11
%retval = select i1 %cmp3, i32 11, i32 %cond
ret i32 %retval
}
; FIXME - vector neglect: FoldAndOfICmps() / FoldOrOfICmps()
define <2 x i32> @test72vec(<2 x i32> %x) {
; CHECK-LABEL: @test72vec(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <2 x i32> %x, <i32 92, i32 92>
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt <2 x i32> %x, <i32 11, i32 11>
; CHECK-NEXT: [[TMP3:%.*]] = and <2 x i1> [[TMP1]], [[TMP2]]
; CHECK-NEXT: [[RETVAL:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> %x, <2 x i32> <i32 11, i32 11>
; CHECK-NEXT: ret <2 x i32> [[RETVAL]]
;
%cmp = icmp sgt <2 x i32> %x, <i32 92, i32 92>
%cond = select <2 x i1> %cmp, <2 x i32> <i32 92, i32 92>, <2 x i32> %x
%cmp3 = icmp sgt <2 x i32> %cond, <i32 11, i32 11>
%retval = select <2 x i1> %cmp3, <2 x i32> <i32 11, i32 11>, <2 x i32> %cond
ret <2 x i32> %retval
}
; MIN(MIN(X, 83), 24) -> MIN(X, 24)
define i32 @test73(i32 %x) {
; CHECK-LABEL: @test73(
; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i32 %x, 24
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[TMP1]], i32 %x, i32 24
; CHECK-NEXT: ret i32 [[RETVAL]]
;
%cmp = icmp ugt i32 %x, 83
%cond = select i1 %cmp, i32 83, i32 %x
%cmp3 = icmp ugt i32 %cond, 24
%retval = select i1 %cmp3, i32 24, i32 %cond
ret i32 %retval
}
; SMAX(SMAX(X, 36), 75) -> SMAX(X, 75)
define i32 @test74(i32 %x) {
; CHECK-LABEL: @test74(
; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 %x, 75
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[TMP1]], i32 %x, i32 75
; CHECK-NEXT: ret i32 [[RETVAL]]
;
%cmp = icmp slt i32 %x, 36
%cond = select i1 %cmp, i32 36, i32 %x
%cmp3 = icmp slt i32 %cond, 75
%retval = select i1 %cmp3, i32 75, i32 %cond
ret i32 %retval
}
; MAX(MAX(X, 47), 68) -> MAX(X, 68)
define i32 @test75(i32 %x) {
; CHECK-LABEL: @test75(
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i32 %x, 68
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[TMP1]], i32 %x, i32 68
; CHECK-NEXT: ret i32 [[RETVAL]]
;
%cmp = icmp ult i32 %x, 47
%cond = select i1 %cmp, i32 47, i32 %x
%cmp3 = icmp ult i32 %cond, 68
%retval = select i1 %cmp3, i32 68, i32 %cond
ret i32 %retval
}