RPCSX/llvm
1
0
Fork 0
mirror of https://github.com/RPCSX/llvm.git synced 2025-01-24 05:09:34 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

[SCEV] Commute sign extends through nsw additions

Browse Source 
Summary: Depends on D13613.

Reviewers: atrick, hfinkel, reames, nlewycky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D13685

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251049 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das 2015-10-22 19:57:25 +00:00
parent c05a5c2c86
commit f606b2f403
2 changed files with 51 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
lib/Analysis/ScalarEvolution.cpp
View File

@ -1631,6 +1631,16 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
}
}
}
// sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
if (SA->getNoWrapFlags(SCEV::FlagNSW)) {
// If the addition does not sign overflow then we can, by definition,
// commute the sign extension with the addition operation.
SmallVector<const SCEV *, 4> Ops;
for (const auto *Op : SA->operands())
Ops.push_back(getSignExtendExpr(Op, Ty));
return getAddExpr(Ops, SCEV::FlagNSW);
}
}
// If the input value is a chrec scev, and we can prove that the value
// did not overflow the old, smaller, value, we can sign extend all of the

41
test/Analysis/ScalarEvolution/no-wrap-add-exprs.ll
View File

@ -42,3 +42,44 @@ define void @f0(i8* %len_addr) {
ret void
}
define void @f1(i8* %len_addr) {
; CHECK-LABEL: Classifying expressions for: @f1
entry:
%len = load i8, i8* %len_addr, !range !0
%len_norange = load i8, i8* %len_addr
; CHECK: %len = load i8, i8* %len_addr, !range !0
; CHECK-NEXT: --> %len U: [0,127) S: [0,127)
; CHECK: %len_norange = load i8, i8* %len_addr
; CHECK-NEXT: --> %len_norange U: full-set S: full-set
%t0 = add i8 %len, -1
%t1 = add i8 %len, -2
; CHECK: %t0 = add i8 %len, -1
; CHECK-NEXT: --> (-1 + %len)<nsw> U: [-1,126) S: [-1,126)
; CHECK: %t1 = add i8 %len, -2
; CHECK-NEXT: --> (-2 + %len)<nsw> U: [-2,125) S: [-2,125)
%t0.sext = sext i8 %t0 to i16
%t1.sext = sext i8 %t1 to i16
; CHECK: %t0.sext = sext i8 %t0 to i16
; CHECK-NEXT: --> (-1 + (zext i8 %len to i16))<nsw> U: [-1,126) S: [-1,126)
; CHECK: %t1.sext = sext i8 %t1 to i16
; CHECK-NEXT: --> (-2 + (zext i8 %len to i16))<nsw> U: [-2,125) S: [-2,125)
%q0 = add i8 %len_norange, 1
%q1 = add i8 %len_norange, 2
; CHECK: %q0 = add i8 %len_norange, 1
; CHECK-NEXT: --> (1 + %len_norange) U: full-set S: full-set
; CHECK: %q1 = add i8 %len_norange, 2
; CHECK-NEXT: --> (2 + %len_norange) U: full-set S: full-set
%q0.sext = sext i8 %q0 to i16
%q1.sext = sext i8 %q1 to i16
; CHECK: %q0.sext = sext i8 %q0 to i16
; CHECK-NEXT: --> (sext i8 (1 + %len_norange) to i16) U: [-128,128) S: [-128,128)
; CHECK: %q1.sext = sext i8 %q1 to i16
; CHECK-NEXT: --> (sext i8 (2 + %len_norange) to i16) U: [-128,128) S: [-128,128)
ret void
}