It enables to work with a smaller constant, which is target friendly for those which can compare to immediates.
It also avoids inserting a shift in favor of a trunc, which can be free on some targets.
This used to work until LLVM-3.1, but regressed with the 3.2 release.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175270
91177308-0d34-0410-b5e6-
96231b3b80d8
return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
And, Constant::getNullValue(And->getType()));
}
+
+ // Transform (icmp pred iM (shl iM %v, N), CI)
+ // -> (icmp pred i(M-N) (trunc %v iM to i(N-N)), (trunc (CI>>N))
+ // Transform the shl to a trunc if (trunc (CI>>N)) has no loss.
+ // This enables to get rid of the shift in favor of a trunc which can be
+ // free on the target. It has the additional benefit of comparing to a
+ // smaller constant, which will be target friendly.
+ unsigned Amt = ShAmt->getLimitedValue(TypeBits-1);
+ if (Amt != 0 && RHSV.countTrailingZeros() >= Amt) {
+ Type *NTy = IntegerType::get(ICI.getContext(), TypeBits - Amt);
+ Constant *NCI = ConstantExpr::getTrunc(
+ ConstantExpr::getAShr(RHS,
+ ConstantInt::get(RHS->getType(), Amt)),
+ NTy);
+ return new ICmpInst(ICI.getPredicate(),
+ Builder->CreateTrunc(LHSI->getOperand(0), NTy),
+ ConstantExpr::getTrunc(NCI, NTy));
+ }
+
break;
}
; PR9998
; Make sure we don't transform the ashr here into an sdiv
; CHECK: @pr9998
-; CHECK: = and i32 %V, 1
-; CHECK: %Z = icmp ne
-; CHECK: ret i1 %Z
+; CHECK: [[BIT:%[A-Za-z0-9.]+]] = and i32 %V, 1
+; CHECK-NEXT: [[CMP:%[A-Za-z0-9.]+]] = icmp ne i32 [[BIT]], 0
+; CHECK-NEXT: ret i1 [[CMP]]
define i1 @pr9998(i32 %V) nounwind {
entry:
%W = shl i32 %V, 31
}
+
; CHECK: @udiv_icmp1
; CHECK: icmp ne i64 %X, 0
define i1 @udiv_icmp1(i64 %X) nounwind {
%3 = or i1 %1, %2
ret i1 %3
}
+
+; CHECK: @icmp_sext16trunc
+; CHECK-NEXT: %1 = trunc i32 %x to i16
+; CHECK-NEXT: %cmp = icmp slt i16 %1, 36
+define i1 @icmp_sext16trunc(i32 %x) {
+ %trunc = trunc i32 %x to i16
+ %sext = sext i16 %trunc to i32
+ %cmp = icmp slt i32 %sext, 36
+ ret i1 %cmp
+}
+
+; CHECK: @icmp_sext8trunc
+; CHECK-NEXT: %1 = trunc i32 %x to i8
+; CHECK-NEXT: %cmp = icmp slt i8 %1, 36
+define i1 @icmp_sext8trunc(i32 %x) {
+ %trunc = trunc i32 %x to i8
+ %sext = sext i8 %trunc to i32
+ %cmp = icmp slt i32 %sext, 36
+ ret i1 %cmp
+}
+
+; CHECK: @icmp_shl16
+; CHECK-NEXT: %1 = trunc i32 %x to i16
+; CHECK-NEXT: %cmp = icmp slt i16 %1, 36
+define i1 @icmp_shl16(i32 %x) {
+ %shl = shl i32 %x, 16
+ %cmp = icmp slt i32 %shl, 2359296
+ ret i1 %cmp
+}
+
+; CHECK: @icmp_shl24
+; CHECK-NEXT: %1 = trunc i32 %x to i8
+; CHECK-NEXT: %cmp = icmp slt i8 %1, 36
+define i1 @icmp_shl24(i32 %x) {
+ %shl = shl i32 %x, 24
+ %cmp = icmp slt i32 %shl, 603979776
+ ret i1 %cmp
+}