[InstCombine] Reduce range of ctpop for non zero argument

xgupta · Jul 28, 2024 · e200439 · e200439
1 parent 4f9b297
commit e200439
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Showing 5 changed files with 16 additions and 11 deletions.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -694,8 +694,13 @@ static Instruction *foldCtpop(IntrinsicInst &II, InstCombinerImpl &IC) {
   // Add range attribute since known bits can't completely reflect what we know.
   if (BitWidth != 1 && !II.hasRetAttr(Attribute::Range) &&
       !II.getMetadata(LLVMContext::MD_range)) {
-    ConstantRange Range(APInt(BitWidth, Known.countMinPopulation()),
-                        APInt(BitWidth, Known.countMaxPopulation() + 1));
+    unsigned KnownMinPop = Known.countMinPopulation();
+    unsigned Lower =
+        KnownMinPop ? KnownMinPop
+                    : isKnownNonZero(
+                          Op0, IC.getSimplifyQuery().getWithInstruction(&II));
+    unsigned Upper = Known.countMaxPopulation() + 1;
+    ConstantRange Range(APInt(BitWidth, Lower), APInt(BitWidth, Upper));
     II.addRangeRetAttr(Range);
     return &II;
   }

diff --git a/llvm/test/Transforms/InstCombine/ctpop-pow2.ll b/llvm/test/Transforms/InstCombine/ctpop-pow2.ll
@@ -60,7 +60,7 @@ define i8 @ctpop_imin_plus1_lshr_nz(i8 %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i8 [[X:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    [[V:%.*]] = lshr i8 -127, [[X]]
-; CHECK-NEXT:    [[CNT:%.*]] = call range(i8 0, 9) i8 @llvm.ctpop.i8(i8 [[V]])
+; CHECK-NEXT:    [[CNT:%.*]] = call range(i8 1, 9) i8 @llvm.ctpop.i8(i8 [[V]])
 ; CHECK-NEXT:    ret i8 [[CNT]]
 ;
   %cmp = icmp ne i8 %x, 0
@@ -104,7 +104,7 @@ define <2 x i32> @ctpop_lshr_intmin_intmin_plus1_vec_nz(<2 x i32> %x) {
 ; CHECK-LABEL: @ctpop_lshr_intmin_intmin_plus1_vec_nz(
 ; CHECK-NEXT:    [[X1:%.*]] = or <2 x i32> [[X:%.*]], <i32 1, i32 1>
 ; CHECK-NEXT:    [[SHR:%.*]] = lshr <2 x i32> <i32 -2147483648, i32 -2147483647>, [[X1]]
-; CHECK-NEXT:    [[CNT:%.*]] = call range(i32 0, 17) <2 x i32> @llvm.ctpop.v2i32(<2 x i32> [[SHR]])
+; CHECK-NEXT:    [[CNT:%.*]] = call range(i32 1, 17) <2 x i32> @llvm.ctpop.v2i32(<2 x i32> [[SHR]])
 ; CHECK-NEXT:    ret <2 x i32> [[CNT]]
 ;
   %x1 = or <2 x i32> %x, <i32 1 ,i32 1>

diff --git a/llvm/test/Transforms/InstCombine/ctpop.ll b/llvm/test/Transforms/InstCombine/ctpop.ll
@@ -488,7 +488,7 @@ define i32 @select_ctpop_zero(i32 %x) {
 
 define i32 @ctpop_non_zero(i32 range(i32 1, 255) %x) {
 ; CHECK-LABEL: @ctpop_non_zero(
-; CHECK-NEXT:    [[CTPOP:%.*]] = call range(i32 0, 9) i32 @llvm.ctpop.i32(i32 [[X:%.*]])
+; CHECK-NEXT:    [[CTPOP:%.*]] = call range(i32 1, 9) i32 @llvm.ctpop.i32(i32 [[X:%.*]])
 ; CHECK-NEXT:    ret i32 [[CTPOP]]
 ;
   %ctpop = call i32 @llvm.ctpop.i32(i32 %x)

diff --git a/llvm/test/Transforms/InstCombine/icmp-ne-pow2.ll b/llvm/test/Transforms/InstCombine/icmp-ne-pow2.ll
@@ -306,7 +306,7 @@ define i32 @pow2_32_nonconst_assume(i32 %x, i32 %y) {
 
 define i32 @pow2_32_gtnonconst_assume(i32 %x, i32 %y) {
 ; CHECK-LABEL: @pow2_32_gtnonconst_assume(
-; CHECK-NEXT:    [[CTPOP:%.*]] = call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[Y:%.*]])
+; CHECK-NEXT:    [[CTPOP:%.*]] = call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 [[Y:%.*]])
 ; CHECK-NEXT:    [[YP2:%.*]] = icmp eq i32 [[CTPOP]], 1
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[YP2]])
 ; CHECK-NEXT:    [[YGT:%.*]] = icmp ugt i32 [[Y]], [[X:%.*]]
@@ -513,7 +513,7 @@ define i32 @maybe_pow2_32_noncont(i32 %x, i32 %y) {
 ; CHECK-NEXT:    [[YGT8:%.*]] = icmp ugt i32 [[Y:%.*]], 8
 ; CHECK-NEXT:    br i1 [[YGT8]], label [[CONT1:%.*]], label [[CONT2:%.*]]
 ; CHECK:       Cont1:
-; CHECK-NEXT:    [[CTPOP:%.*]] = call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[Y]])
+; CHECK-NEXT:    [[CTPOP:%.*]] = call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 [[Y]])
 ; CHECK-NEXT:    [[YP2:%.*]] = icmp eq i32 [[CTPOP]], 1
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[YP2]])
 ; CHECK-NEXT:    br i1 true, label [[CONT2]], label [[FALSE:%.*]]

diff --git a/llvm/test/Transforms/InstCombine/ispow2.ll b/llvm/test/Transforms/InstCombine/ispow2.ll
@@ -197,7 +197,7 @@ define i1 @is_pow2_non_zero_ult_2(i32 %x) {
 ; CHECK-LABEL: @is_pow2_non_zero_ult_2(
 ; CHECK-NEXT:    [[NOTZERO:%.*]] = icmp ne i32 [[X:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[NOTZERO]])
-; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
+; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 [[X]])
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[T0]], 2
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
@@ -212,7 +212,7 @@ define i1 @is_pow2_non_zero_eq_1(i32 %x) {
 ; CHECK-LABEL: @is_pow2_non_zero_eq_1(
 ; CHECK-NEXT:    [[NOTZERO:%.*]] = icmp ne i32 [[X:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[NOTZERO]])
-; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
+; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 [[X]])
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[T0]], 1
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
@@ -227,7 +227,7 @@ define i1 @is_pow2_non_zero_ugt_1(i32 %x) {
 ; CHECK-LABEL: @is_pow2_non_zero_ugt_1(
 ; CHECK-NEXT:    [[NOTZERO:%.*]] = icmp ne i32 [[X:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[NOTZERO]])
-; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
+; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 [[X]])
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i32 [[T0]], 1
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
@@ -242,7 +242,7 @@ define i1 @is_pow2_non_zero_ne_1(i32 %x) {
 ; CHECK-LABEL: @is_pow2_non_zero_ne_1(
 ; CHECK-NEXT:    [[NOTZERO:%.*]] = icmp ne i32 [[X:%.*]], 0
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[NOTZERO]])
-; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
+; CHECK-NEXT:    [[T0:%.*]] = tail call range(i32 1, 33) i32 @llvm.ctpop.i32(i32 [[X]])
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[T0]], 1
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;