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[NFC][CVP] Add tests where we can replace sext with zext 

If the sign bit of the value that is being sign-extended is not set,
i.e. the value is non-negative (s>= 0), then zero-extension will suffice,
and is better for analysis: https://rise4fun.com/Alive/a8PD

llvm-svn: 374075
This commit is contained in:
Roman Lebedev 2019-10-08 16:21:13 +00:00
parent 7df5b2f79f
commit d1fe34cc93
1 changed files with 107 additions and 0 deletions
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107
llvm/test/Transforms/CorrelatedValuePropagation/sext.ll Normal file
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -correlated-propagation -S | FileCheck %s
; Check that debug locations are preserved. For more info see:
; https://llvm.org/docs/SourceLevelDebugging.html#fixing-errors
; RUN: opt < %s -enable-debugify -correlated-propagation -S 2>&1 | \
; RUN: FileCheck %s -check-prefix=DEBUG
; DEBUG: CheckModuleDebugify: PASS
declare void @use64(i64)
define void @test1(i32 %n) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[A:%.*]] = phi i32 [ [[N:%.*]], [[ENTRY:%.*]] ], [ [[EXT:%.*]], [[FOR_BODY:%.*]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A]], 1
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[EXT_WIDE:%.*]] = sext i32 [[A]] to i64
; CHECK-NEXT: call void @use64(i64 [[EXT_WIDE]])
; CHECK-NEXT: [[EXT]] = trunc i64 [[EXT_WIDE]] to i32
; CHECK-NEXT: br label [[FOR_COND]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.cond
for.cond: ; preds = %for.body, %entry
%a = phi i32 [ %n, %entry ], [ %ext, %for.body ]
%cmp = icmp sgt i32 %a, 1
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%ext.wide = sext i32 %a to i64
call void @use64(i64 %ext.wide)
%ext = trunc i64 %ext.wide to i32
br label %for.cond
for.end: ; preds = %for.cond
ret void
}
;; Negative test to show transform doesn't happen unless n > 0.
define void @test2(i32 %n) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[A:%.*]] = phi i32 [ [[N:%.*]], [[ENTRY:%.*]] ], [ [[EXT:%.*]], [[FOR_BODY:%.*]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[A]], -2
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[EXT_WIDE:%.*]] = sext i32 [[A]] to i64
; CHECK-NEXT: call void @use64(i64 [[EXT_WIDE]])
; CHECK-NEXT: [[EXT]] = trunc i64 [[EXT_WIDE]] to i32
; CHECK-NEXT: br label [[FOR_COND]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.cond
for.cond: ; preds = %for.body, %entry
%a = phi i32 [ %n, %entry ], [ %ext, %for.body ]
%cmp = icmp sgt i32 %a, -2
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%ext.wide = sext i32 %a to i64
call void @use64(i64 %ext.wide)
%ext = trunc i64 %ext.wide to i32
br label %for.cond
for.end: ; preds = %for.cond
ret void
}
;; Non looping test case.
define void @test3(i32 %n) {
; CHECK-LABEL: @test3(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i32 [[N:%.*]], 0
; CHECK-NEXT: br i1 [[CMP]], label [[BB:%.*]], label [[EXIT:%.*]]
; CHECK: bb:
; CHECK-NEXT: [[EXT_WIDE:%.*]] = sext i32 [[N]] to i64
; CHECK-NEXT: call void @use64(i64 [[EXT_WIDE]])
; CHECK-NEXT: [[EXT:%.*]] = trunc i64 [[EXT_WIDE]] to i32
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entry:
%cmp = icmp sgt i32 %n, 0
br i1 %cmp, label %bb, label %exit
bb:
%ext.wide = sext i32 %n to i64
call void @use64(i64 %ext.wide)
%ext = trunc i64 %ext.wide to i32
br label %exit
exit:
ret void
}