[ValueTracking] add range limits for cttz
As discussed in D89952,
instcombine can sometimes find a way to reduce similar patterns,
but it is incomplete.
InstSimplify uses the computeConstantRange() ValueTracking analysis
via simplifyICmpWithConstant(), so we just need to fill in the max
value of cttz to process any "icmp pred cttz(X), C" pattern (the
min value is initialized to zero automatically).
https://alive2.llvm.org/ce/z/Z_SLWZ
Follow-up to D89976.
GitOrigin-RevId: c72198079df60e73948fe4744b1c0ef7231803fd
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index e277b02..2364208 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -6462,6 +6462,7 @@
switch (II.getIntrinsicID()) {
case Intrinsic::ctpop:
case Intrinsic::ctlz:
+ case Intrinsic::cttz:
// Maximum of set/clear bits is the bit width.
assert(Lower == 0 && "Expected lower bound to be zero");
Upper = Width + 1;
diff --git a/test/Transforms/InstCombine/ctpop-cttz.ll b/test/Transforms/InstCombine/ctpop-cttz.ll
index 6ac3cfe..59a45f3 100644
--- a/test/Transforms/InstCombine/ctpop-cttz.ll
+++ b/test/Transforms/InstCombine/ctpop-cttz.ll
@@ -21,7 +21,7 @@
define <2 x i32> @ctpop1v(<2 x i32> %0) {
; CHECK-LABEL: @ctpop1v(
; CHECK-NEXT: [[TMP2:%.*]] = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> [[TMP0:%.*]], i1 false)
-; CHECK-NEXT: [[TMP3:%.*]] = sub nsw <2 x i32> <i32 32, i32 32>, [[TMP2]]
+; CHECK-NEXT: [[TMP3:%.*]] = sub nuw nsw <2 x i32> <i32 32, i32 32>, [[TMP2]]
; CHECK-NEXT: ret <2 x i32> [[TMP3]]
;
%2 = sub <2 x i32> zeroinitializer, %0
diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll
index d024d70..5afa05b 100644
--- a/test/Transforms/InstSimplify/compare.ll
+++ b/test/Transforms/InstSimplify/compare.ll
@@ -2259,9 +2259,7 @@
define i1 @cttz_sgt_bitwidth(i11 %x) {
; CHECK-LABEL: @cttz_sgt_bitwidth(
-; CHECK-NEXT: [[POP:%.*]] = call i11 @llvm.cttz.i11(i11 [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i11 [[POP]], 11
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%pop = call i11 @llvm.cttz.i11(i11 %x)
%cmp = icmp sgt i11 %pop, 11
@@ -2270,9 +2268,7 @@
define i1 @cttz_sle_minus1(i11 %x) {
; CHECK-LABEL: @cttz_sle_minus1(
-; CHECK-NEXT: [[POP:%.*]] = call i11 @llvm.cttz.i11(i11 [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sle i11 [[POP]], -1
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%pop = call i11 @llvm.cttz.i11(i11 %x)
%cmp = icmp sle i11 %pop, -1
@@ -2281,9 +2277,7 @@
define i1 @cttz_ugt_bitwidth(i73 %x) {
; CHECK-LABEL: @cttz_ugt_bitwidth(
-; CHECK-NEXT: [[POP:%.*]] = call i73 @llvm.cttz.i73(i73 [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i73 [[POP]], 73
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 false
;
%pop = call i73 @llvm.cttz.i73(i73 %x)
%cmp = icmp ugt i73 %pop, 73
@@ -2305,9 +2299,7 @@
define <2 x i1> @cttz_sgt_bitwidth_splat(<2 x i13> %x) {
; CHECK-LABEL: @cttz_sgt_bitwidth_splat(
-; CHECK-NEXT: [[POP:%.*]] = call <2 x i13> @llvm.cttz.v2i13(<2 x i13> [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp sgt <2 x i13> [[POP]], <i13 13, i13 13>
-; CHECK-NEXT: ret <2 x i1> [[CMP]]
+; CHECK-NEXT: ret <2 x i1> zeroinitializer
;
%pop = call <2 x i13> @llvm.cttz.v2i13(<2 x i13> %x)
%cmp = icmp sgt <2 x i13> %pop, <i13 13, i13 13>
@@ -2316,9 +2308,7 @@
define i1 @cttz_ult_plus1_bitwidth(i11 %x) {
; CHECK-LABEL: @cttz_ult_plus1_bitwidth(
-; CHECK-NEXT: [[POP:%.*]] = call i11 @llvm.cttz.i11(i11 [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i11 [[POP]], 12
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%pop = call i11 @llvm.cttz.i11(i11 %x)
%cmp = icmp ult i11 %pop, 12
@@ -2327,9 +2317,7 @@
define i1 @cttz_ne_big_bitwidth(i73 %x) {
; CHECK-LABEL: @cttz_ne_big_bitwidth(
-; CHECK-NEXT: [[POP:%.*]] = call i73 @llvm.cttz.i73(i73 [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp ne i73 [[POP]], 75
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%pop = call i73 @llvm.cttz.i73(i73 %x)
%cmp = icmp ne i73 %pop, 75
@@ -2338,9 +2326,7 @@
define <2 x i1> @cttz_slt_bitwidth_plus1_splat(<2 x i13> %x) {
; CHECK-LABEL: @cttz_slt_bitwidth_plus1_splat(
-; CHECK-NEXT: [[POP:%.*]] = call <2 x i13> @llvm.cttz.v2i13(<2 x i13> [[X:%.*]], i1 false)
-; CHECK-NEXT: [[CMP:%.*]] = icmp slt <2 x i13> [[POP]], <i13 14, i13 14>
-; CHECK-NEXT: ret <2 x i1> [[CMP]]
+; CHECK-NEXT: ret <2 x i1> <i1 true, i1 true>
;
%pop = call <2 x i13> @llvm.cttz.v2i13(<2 x i13> %x)
%cmp = icmp slt <2 x i13> %pop, <i13 14, i13 14>
