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[InstCombine] Ensure that truncated int types are legal. 

Fixes the FIXMEs in D25952 and rL285075.

Patch by bryant!

Differential Revision: https://reviews.llvm.org/D25955

llvm-svn: 285108
This commit is contained in:
Sanjay Patel 2016-10-25 20:11:47 +00:00
parent f6c4ab901b
commit f3dda13bd2
3 changed files with 9 additions and 12 deletions
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6
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -1950,9 +1950,6 @@ Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp,
And, Constant::getNullValue(And->getType()));
}
// FIXME: This transform can create illegal types. Use the DataLayout to
// decide when to try this?
// Transform (icmp pred iM (shl iM %v, N), C)
// -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N))
// Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N.
@ -1960,7 +1957,8 @@ Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp,
// free on the target. It has the additional benefit of comparing to a
// smaller constant, which will be target friendly.
unsigned Amt = ShiftAmt->getLimitedValue(TypeBits - 1);
if (Shl->hasOneUse() && Amt != 0 && C->countTrailingZeros() >= Amt) {
if (Shl->hasOneUse() && Amt != 0 && C->countTrailingZeros() >= Amt &&
DL.isLegalInteger(TypeBits - Amt)) {
Type *TruncTy = IntegerType::get(Cmp.getContext(), TypeBits - Amt);
if (X->getType()->isVectorTy())
TruncTy = VectorType::get(TruncTy, X->getType()->getVectorNumElements());

9
llvm/test/Transforms/InstCombine/icmp-shl-nuw.ll
View File

@ -14,8 +14,8 @@ define i1 @icmp_ugt_32(i64) {
define i1 @icmp_ule_64(i128) {
; CHECK-LABEL: @icmp_ule_64(
; CHECK-NEXT: [[TMP2:%.*]] = trunc i128 %0 to i64
; CHECK-NEXT: [[D:%.*]] = icmp eq i64 [[TMP2]], 0
; CHECK-NEXT: [[C:%.*]] = shl nuw i128 %0, 64
; CHECK-NEXT: [[D:%.*]] = icmp ult i128 [[C]], 18446744073709551616
; CHECK-NEXT: ret i1 [[D]]
;
%c = shl nuw i128 %0, 64
@ -34,11 +34,10 @@ define i1 @icmp_ugt_16(i64) {
ret i1 %d
}
; FIXME: InstCombine ought not to emit the potentially illegal i48.
define <2 x i1> @icmp_ule_16x2(<2 x i64>) {
; CHECK-LABEL: @icmp_ule_16x2(
; CHECK-NEXT: [[TMP2:%.*]] = trunc <2 x i64> %0 to <2 x i48>
; CHECK-NEXT: [[D:%.*]] = icmp eq <2 x i48> [[TMP2]], zeroinitializer
; CHECK-NEXT: [[C:%.*]] = shl nuw <2 x i64> %0, <i64 16, i64 16>
; CHECK-NEXT: [[D:%.*]] = icmp ult <2 x i64> [[C]], <i64 65536, i64 65536>
; CHECK-NEXT: ret <2 x i1> [[D]]
;
%c = shl nuw <2 x i64> %0, <i64 16, i64 16>

6
llvm/test/Transforms/InstCombine/icmp.ll
View File

@ -1208,12 +1208,12 @@ define i1 @icmp_shl16(i32 %x) {
ret i1 %cmp
}
; FIXME: We shouldn't be creating illegal types like i15 in InstCombine.
; D25952: Don't create illegal types like i15 in InstCombine
define i1 @icmp_shl17(i32 %x) {
; CHECK-LABEL: @icmp_shl17(
; CHECK-NEXT: [[TMP1:%.*]] = trunc i32 %x to i15
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i15 [[TMP1]], 18
; CHECK-NEXT: [[SHL:%.*]] = shl i32 %x, 17
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[SHL]], 2359296
; CHECK-NEXT: ret i1 [[CMP]]
;
%shl = shl i32 %x, 17