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archived-llvm/test/CodeGen/PowerPC/cmp_elimination.ll
Hiroshi Inoue 7166ffbe09 [PowerPC] eliminate redundant compare instruction 
If multiple conditional branches are executed based on the same comparison, we can execute multiple conditional branches based on the result of one comparison on PPC. For example,

if (a == 0) { ... }
else if (a < 0) { ... }

can be executed by one compare and two conditional branches instead of two pairs of a compare and a conditional branch.

This patch identifies a code sequence of the two pairs of a compare and a conditional branch and merge the compares if possible.
To maximize the opportunity, we do canonicalization of code sequence before merging compares.
For the above example, the input for this pass looks like:

cmplwi r3, 0
beq    0, .LBB0_3
cmpwi  r3, -1
bgt    0, .LBB0_4

So, before merging two compares, we canonicalize it as

cmpwi  r3, 0       ; cmplwi and cmpwi yield same result for beq
beq    0, .LBB0_3
cmpwi  r3, 0       ; greather than -1 means greater or equal to 0
bge    0, .LBB0_4

The generated code should be

cmpwi  r3, 0
beq    0, .LBB0_3
bge    0, .LBB0_4

Differential Revision: https://reviews.llvm.org/D37211



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312514 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-05 04:15:17 +00:00

723 lines
12 KiB
LLVM
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; RUN: llc -verify-machineinstrs < %s -mtriple=powerpc64-unknown-linux-gnu | FileCheck %s
; RUN: llc -verify-machineinstrs < %s -mtriple=powerpc64le-unknown-linux-gnu | FileCheck %s
; Test cases for compare elimination in PPCMIPeephole pass
define void @func1(i32 signext %a) {
; We should have only one compare instruction
; CHECK-LABEL: @func1
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i32 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp slt i32 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func2(i32 signext %a) {
; CHECK-LABEL: @func2
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i32 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i32 %a, 100
br i1 %cmp1, label %if.end3, label %if.then2
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func3(i32 signext %a) {
; CHECK-LABEL: @func3
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp sgt i32 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i32 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func4(i32 zeroext %a) {
; CHECK-LABEL: @func4
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i32 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp ult i32 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func5(i32 zeroext %a) {
; CHECK-LABEL: @func5
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ult i32 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i32 %a, 100
br i1 %cmp1, label %if.end3, label %if.then2
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func6(i32 zeroext %a) {
; CHECK-LABEL: @func6
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ugt i32 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i32 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func7(i64 %a) {
; CHECK-LABEL: @func7
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i64 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp slt i64 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func8(i64 %a) {
; CHECK-LABEL: @func8
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i64 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i64 %a, 100
br i1 %cmp1, label %if.end3, label %if.then2
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func9(i64 %a) {
; CHECK-LABEL: @func9
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp sgt i64 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i64 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func10(i64 %a) {
; CHECK-LABEL: @func10
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i64 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp ult i64 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func11(i64 %a) {
; CHECK-LABEL: @func11
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ult i64 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i64 %a, 100
br i1 %cmp1, label %if.end3, label %if.then2
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func12(i64 %a) {
; CHECK-LABEL: @func12
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ugt i64 %a, 100
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i64 %a, 100
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func13(i32 signext %a, i32 signext %b) {
; CHECK-LABEL: @func13
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i32 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp slt i32 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func14(i32 signext %a, i32 signext %b) {
; CHECK-LABEL: @func14
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i32 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp sgt i32 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func15(i32 signext %a, i32 signext %b) {
; CHECK-LABEL: @func15
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i32 %b, %a
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i32 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func16(i32 zeroext %a, i32 zeroext %b) {
; CHECK-LABEL: @func16
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i32 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp ult i32 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func17(i32 zeroext %a, i32 zeroext %b) {
; CHECK-LABEL: @func17
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ult i32 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp ugt i32 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func18(i32 zeroext %a, i32 zeroext %b) {
; CHECK-LABEL: @func18
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ult i32 %b, %a
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i32 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func19(i64 %a, i64 %b) {
; CHECK-LABEL: @func19
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i64 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp slt i64 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func20(i64 %a, i64 %b) {
; CHECK-LABEL: @func20
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i64 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp sgt i64 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func21(i64 %a, i64 %b) {
; CHECK-LABEL: @func21
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i64 %b, %a
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i64 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func22(i64 %a, i64 %b) {
; CHECK-LABEL: @func22
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp eq i64 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp ult i64 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func23(i64 %a, i64 %b) {
; CHECK-LABEL: @func23
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ult i64 %a, %b
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp ugt i64 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func24(i64 %a, i64 %b) {
; CHECK-LABEL: @func24
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp ult i64 %b, %a
br i1 %cmp, label %if.then, label %if.else
if.then:
tail call void @dummy1()
br label %if.end3
if.else:
%cmp1 = icmp eq i64 %a, %b
br i1 %cmp1, label %if.then2, label %if.end3
if.then2:
tail call void @dummy2()
br label %if.end3
if.end3:
ret void
}
define void @func25(i64 %a, i64 %b) {
; CHECK-LABEL: @func25
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp slt i64 %b, %a
br i1 %cmp, label %if.then, label %if.else, !prof !1
if.then:
tail call void @dummy1()
br label %if.end6
if.else:
%cmp2 = icmp eq i64 %a, %b
br i1 %cmp2, label %if.then4, label %if.else5
if.then4:
tail call void @dummy2()
br label %if.end6
if.else5:
tail call void @dummy3()
br label %if.end6
if.end6:
ret void
}
define void @func26(i32 signext %a) {
; CHECK-LABEL: @func26
; CHECK: cmp
; CHECK-NOT: cmp
; CHECK: blr
entry:
%cmp = icmp sgt i32 %a, 0
br i1 %cmp, label %if.then, label %if.else, !prof !2
if.then:
tail call void @dummy1()
br label %if.end9
if.else:
%cmp2 = icmp eq i32 %a, 0
br i1 %cmp2, label %if.then7, label %if.else8, !prof !2
if.then7:
tail call void @dummy2()
br label %if.end9
if.else8:
tail call void @dummy3()
br label %if.end9
if.end9:
ret void
}
@g1 = external local_unnamed_addr global i32, align 4
@g2 = external local_unnamed_addr global i32, align 4
define void @func27(i32 signext %a) {
; CHECK-LABEL: @func27
; CHECK: cmp
; CHECK: beq
; CHECK-NOT: cmp
; CHECK: bgelr
; CHECK: blr
entry:
%cmp = icmp eq i32 %a, 0
br i1 %cmp, label %if.end3.sink.split, label %if.else
if.else:
%cmp1 = icmp slt i32 %a, 0
br i1 %cmp1, label %if.end3.sink.split, label %if.end
if.end3.sink.split:
%g2.sink = phi i32* [ @g2, %if.else ], [ @g1, %entry ]
store i32 0, i32* %g2.sink, align 4
br label %if.end
if.end:
ret void
}
declare void @dummy1()
declare void @dummy2()
declare void @dummy3()
!1 = !{!"branch_weights", i32 2000, i32 1}
!2 = !{!"branch_weights", i32 1, i32 2000}
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