[ValueTracking] Perform a local edge implication check for isKnownNonNegative #72437
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…Negative This handles the idiomatic case of an instruction in the preheader of a loop with a loop guard on whether the starting value of the IV is non negative. Note that we have many other examples of isKnownX queries which perform tree walks to try and prove the required condition. This patch is quite limited in checking only an immediate guarding condition.
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@llvm/pr-subscribers-llvm-analysis @llvm/pr-subscribers-llvm-transforms Author: Philip Reames (preames) ChangesThis handles the idiomatic case of an instruction in the preheader of a loop with a loop guard on whether the starting value of the IV is non negative. Note that we have many other examples of isKnownX queries which perform tree walks to try and prove the required condition. This patch is quite limited in checking only an immediate guarding condition. Patch is 40.58 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/72437.diff 10 Files Affected:
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 5f5d7e07cac1e46..22e88cb2f52534d 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -291,7 +291,14 @@ bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL,
const Instruction *CxtI, const DominatorTree *DT,
bool UseInstrInfo) {
KnownBits Known = computeKnownBits(V, DL, Depth, AC, CxtI, DT, UseInstrInfo);
- return Known.isNonNegative();
+ if (Known.isNonNegative())
+ return true;
+
+ // Look at the immediate proceeding branch to see if it establishes the
+ // condition we need.
+ return isImpliedByDomCondition(ICmpInst::ICMP_SGE, V,
+ Constant::getNullValue(V->getType()), CxtI,
+ DL).value_or(false);
}
bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth,
diff --git a/llvm/test/Transforms/InstCombine/sub-of-negatible-inseltpoison.ll b/llvm/test/Transforms/InstCombine/sub-of-negatible-inseltpoison.ll
index 1b574e2e394e73d..dd72f797916459d 100644
--- a/llvm/test/Transforms/InstCombine/sub-of-negatible-inseltpoison.ll
+++ b/llvm/test/Transforms/InstCombine/sub-of-negatible-inseltpoison.ll
@@ -865,7 +865,7 @@ define i16 @negation_of_zeroext_of_nonnegative(i8 %x) {
; CHECK-NEXT: [[T1:%.*]] = icmp sgt i8 [[T0]], -1
; CHECK-NEXT: br i1 [[T1]], label [[NONNEG_BB:%.*]], label [[NEG_BB:%.*]]
; CHECK: nonneg_bb:
-; CHECK-NEXT: [[T2:%.*]] = zext i8 [[T0]] to i16
+; CHECK-NEXT: [[T2:%.*]] = zext nneg i8 [[T0]] to i16
; CHECK-NEXT: [[T3:%.*]] = sub nsw i16 0, [[T2]]
; CHECK-NEXT: ret i16 [[T3]]
; CHECK: neg_bb:
@@ -889,7 +889,7 @@ define i16 @negation_of_zeroext_of_positive(i8 %x) {
; CHECK-NEXT: [[T1:%.*]] = icmp sgt i8 [[T0]], 0
; CHECK-NEXT: br i1 [[T1]], label [[NONNEG_BB:%.*]], label [[NEG_BB:%.*]]
; CHECK: nonneg_bb:
-; CHECK-NEXT: [[T2:%.*]] = zext i8 [[T0]] to i16
+; CHECK-NEXT: [[T2:%.*]] = zext nneg i8 [[T0]] to i16
; CHECK-NEXT: [[T3:%.*]] = sub nsw i16 0, [[T2]]
; CHECK-NEXT: ret i16 [[T3]]
; CHECK: neg_bb:
@@ -961,7 +961,7 @@ define i16 @negation_of_signext_of_nonnegative__wrong_cast(i8 %x) {
; CHECK-NEXT: [[T1:%.*]] = icmp sgt i8 [[T0]], -1
; CHECK-NEXT: br i1 [[T1]], label [[NONNEG_BB:%.*]], label [[NEG_BB:%.*]]
; CHECK: nonneg_bb:
-; CHECK-NEXT: [[T2:%.*]] = sext i8 [[T0]] to i16
+; CHECK-NEXT: [[T2:%.*]] = zext nneg i8 [[T0]] to i16
; CHECK-NEXT: [[T3:%.*]] = sub nsw i16 0, [[T2]]
; CHECK-NEXT: ret i16 [[T3]]
; CHECK: neg_bb:
diff --git a/llvm/test/Transforms/InstCombine/sub-of-negatible.ll b/llvm/test/Transforms/InstCombine/sub-of-negatible.ll
index 1bea723a1ca1286..f653ae7acf8a611 100644
--- a/llvm/test/Transforms/InstCombine/sub-of-negatible.ll
+++ b/llvm/test/Transforms/InstCombine/sub-of-negatible.ll
@@ -889,7 +889,7 @@ define i16 @negation_of_zeroext_of_nonnegative(i8 %x) {
; CHECK-NEXT: [[T1:%.*]] = icmp sgt i8 [[T0]], -1
; CHECK-NEXT: br i1 [[T1]], label [[NONNEG_BB:%.*]], label [[NEG_BB:%.*]]
; CHECK: nonneg_bb:
-; CHECK-NEXT: [[T2:%.*]] = zext i8 [[T0]] to i16
+; CHECK-NEXT: [[T2:%.*]] = zext nneg i8 [[T0]] to i16
; CHECK-NEXT: [[T3:%.*]] = sub nsw i16 0, [[T2]]
; CHECK-NEXT: ret i16 [[T3]]
; CHECK: neg_bb:
@@ -913,7 +913,7 @@ define i16 @negation_of_zeroext_of_positive(i8 %x) {
; CHECK-NEXT: [[T1:%.*]] = icmp sgt i8 [[T0]], 0
; CHECK-NEXT: br i1 [[T1]], label [[NONNEG_BB:%.*]], label [[NEG_BB:%.*]]
; CHECK: nonneg_bb:
-; CHECK-NEXT: [[T2:%.*]] = zext i8 [[T0]] to i16
+; CHECK-NEXT: [[T2:%.*]] = zext nneg i8 [[T0]] to i16
; CHECK-NEXT: [[T3:%.*]] = sub nsw i16 0, [[T2]]
; CHECK-NEXT: ret i16 [[T3]]
; CHECK: neg_bb:
@@ -985,7 +985,7 @@ define i16 @negation_of_signext_of_nonnegative__wrong_cast(i8 %x) {
; CHECK-NEXT: [[T1:%.*]] = icmp sgt i8 [[T0]], -1
; CHECK-NEXT: br i1 [[T1]], label [[NONNEG_BB:%.*]], label [[NEG_BB:%.*]]
; CHECK: nonneg_bb:
-; CHECK-NEXT: [[T2:%.*]] = sext i8 [[T0]] to i16
+; CHECK-NEXT: [[T2:%.*]] = zext nneg i8 [[T0]] to i16
; CHECK-NEXT: [[T3:%.*]] = sub nsw i16 0, [[T2]]
; CHECK-NEXT: ret i16 [[T3]]
; CHECK: neg_bb:
diff --git a/llvm/test/Transforms/LoopVectorize/float-induction.ll b/llvm/test/Transforms/LoopVectorize/float-induction.ll
index 44f3c3db26d9514..da2d8eb1b41666d 100644
--- a/llvm/test/Transforms/LoopVectorize/float-induction.ll
+++ b/llvm/test/Transforms/LoopVectorize/float-induction.ll
@@ -24,11 +24,11 @@ define void @fp_iv_loop1_fast_FMF(float %init, ptr noalias nocapture %A, i32 %N)
; VEC4_INTERL1-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL1: for.body.lr.ph:
; VEC4_INTERL1-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL1-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 4
; VEC4_INTERL1-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL1: vector.ph:
-; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967292
+; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483644
; VEC4_INTERL1-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL1-NEXT: [[TMP1:%.*]] = fmul fast float [[FPINC]], [[DOTCAST]]
; VEC4_INTERL1-NEXT: [[IND_END:%.*]] = fsub fast float [[INIT:%.*]], [[TMP1]]
@@ -79,11 +79,11 @@ define void @fp_iv_loop1_fast_FMF(float %init, ptr noalias nocapture %A, i32 %N)
; VEC4_INTERL2-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL2: for.body.lr.ph:
; VEC4_INTERL2-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 8
; VEC4_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL2: vector.ph:
-; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967288
+; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483640
; VEC4_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL2-NEXT: [[TMP1:%.*]] = fmul fast float [[FPINC]], [[DOTCAST]]
; VEC4_INTERL2-NEXT: [[IND_END:%.*]] = fsub fast float [[INIT:%.*]], [[TMP1]]
@@ -137,11 +137,11 @@ define void @fp_iv_loop1_fast_FMF(float %init, ptr noalias nocapture %A, i32 %N)
; VEC1_INTERL2-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC1_INTERL2: for.body.lr.ph:
; VEC1_INTERL2-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC1_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC1_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC1_INTERL2: vector.ph:
-; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967294
+; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483646
; VEC1_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC1_INTERL2-NEXT: [[TMP1:%.*]] = fmul fast float [[FPINC]], [[DOTCAST]]
; VEC1_INTERL2-NEXT: [[IND_END:%.*]] = fsub fast float [[INIT:%.*]], [[TMP1]]
@@ -188,11 +188,11 @@ define void @fp_iv_loop1_fast_FMF(float %init, ptr noalias nocapture %A, i32 %N)
; VEC2_INTERL1_PRED_STORE-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC2_INTERL1_PRED_STORE: for.body.lr.ph:
; VEC2_INTERL1_PRED_STORE-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC2_INTERL1_PRED_STORE-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC2_INTERL1_PRED_STORE-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[FOR_BODY:%.*]], label [[VECTOR_PH:%.*]]
; VEC2_INTERL1_PRED_STORE: vector.ph:
-; VEC2_INTERL1_PRED_STORE-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967294
+; VEC2_INTERL1_PRED_STORE-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483646
; VEC2_INTERL1_PRED_STORE-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP1:%.*]] = fmul fast float [[FPINC]], [[DOTCAST]]
; VEC2_INTERL1_PRED_STORE-NEXT: [[IND_END:%.*]] = fsub fast float [[INIT:%.*]], [[TMP1]]
@@ -271,11 +271,11 @@ define void @fp_iv_loop1_reassoc_FMF(float %init, ptr noalias nocapture %A, i32
; VEC4_INTERL1-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL1: for.body.lr.ph:
; VEC4_INTERL1-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL1-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 4
; VEC4_INTERL1-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL1: vector.ph:
-; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967292
+; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483644
; VEC4_INTERL1-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL1-NEXT: [[TMP1:%.*]] = fmul reassoc float [[FPINC]], [[DOTCAST]]
; VEC4_INTERL1-NEXT: [[IND_END:%.*]] = fsub reassoc float [[INIT:%.*]], [[TMP1]]
@@ -326,11 +326,11 @@ define void @fp_iv_loop1_reassoc_FMF(float %init, ptr noalias nocapture %A, i32
; VEC4_INTERL2-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL2: for.body.lr.ph:
; VEC4_INTERL2-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 8
; VEC4_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL2: vector.ph:
-; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967288
+; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483640
; VEC4_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL2-NEXT: [[TMP1:%.*]] = fmul reassoc float [[FPINC]], [[DOTCAST]]
; VEC4_INTERL2-NEXT: [[IND_END:%.*]] = fsub reassoc float [[INIT:%.*]], [[TMP1]]
@@ -384,11 +384,11 @@ define void @fp_iv_loop1_reassoc_FMF(float %init, ptr noalias nocapture %A, i32
; VEC1_INTERL2-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC1_INTERL2: for.body.lr.ph:
; VEC1_INTERL2-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC1_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC1_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC1_INTERL2: vector.ph:
-; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967294
+; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483646
; VEC1_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC1_INTERL2-NEXT: [[TMP1:%.*]] = fmul reassoc float [[FPINC]], [[DOTCAST]]
; VEC1_INTERL2-NEXT: [[IND_END:%.*]] = fsub reassoc float [[INIT:%.*]], [[TMP1]]
@@ -437,11 +437,11 @@ define void @fp_iv_loop1_reassoc_FMF(float %init, ptr noalias nocapture %A, i32
; VEC2_INTERL1_PRED_STORE-NEXT: br i1 [[CMP4]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC2_INTERL1_PRED_STORE: for.body.lr.ph:
; VEC2_INTERL1_PRED_STORE-NEXT: [[FPINC:%.*]] = load float, ptr @fp_inc, align 4
-; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC2_INTERL1_PRED_STORE-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC2_INTERL1_PRED_STORE-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[FOR_BODY:%.*]], label [[VECTOR_PH:%.*]]
; VEC2_INTERL1_PRED_STORE: vector.ph:
-; VEC2_INTERL1_PRED_STORE-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967294
+; VEC2_INTERL1_PRED_STORE-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483646
; VEC2_INTERL1_PRED_STORE-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP1:%.*]] = fmul reassoc float [[FPINC]], [[DOTCAST]]
; VEC2_INTERL1_PRED_STORE-NEXT: [[IND_END:%.*]] = fsub reassoc float [[INIT:%.*]], [[TMP1]]
@@ -521,11 +521,11 @@ define void @fp_iv_loop2(float %init, ptr noalias nocapture %A, i32 %N) #0 {
; VEC4_INTERL1-NEXT: [[CMP4:%.*]] = icmp sgt i32 [[N:%.*]], 0
; VEC4_INTERL1-NEXT: br i1 [[CMP4]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL1: for.body.preheader:
-; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL1-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 4
; VEC4_INTERL1-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL1: vector.ph:
-; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967292
+; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483644
; VEC4_INTERL1-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL1-NEXT: [[TMP1:%.*]] = fmul fast float [[DOTCAST]], 5.000000e-01
; VEC4_INTERL1-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP1]], [[INIT:%.*]]
@@ -569,11 +569,11 @@ define void @fp_iv_loop2(float %init, ptr noalias nocapture %A, i32 %N) #0 {
; VEC4_INTERL2-NEXT: [[CMP4:%.*]] = icmp sgt i32 [[N:%.*]], 0
; VEC4_INTERL2-NEXT: br i1 [[CMP4]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL2: for.body.preheader:
-; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 8
; VEC4_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL2: vector.ph:
-; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967288
+; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483640
; VEC4_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL2-NEXT: [[TMP1:%.*]] = fmul fast float [[DOTCAST]], 5.000000e-01
; VEC4_INTERL2-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP1]], [[INIT:%.*]]
@@ -620,11 +620,11 @@ define void @fp_iv_loop2(float %init, ptr noalias nocapture %A, i32 %N) #0 {
; VEC1_INTERL2-NEXT: [[CMP4:%.*]] = icmp sgt i32 [[N:%.*]], 0
; VEC1_INTERL2-NEXT: br i1 [[CMP4]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_END:%.*]]
; VEC1_INTERL2: for.body.preheader:
-; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC1_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC1_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC1_INTERL2: vector.ph:
-; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967294
+; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483646
; VEC1_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC1_INTERL2-NEXT: [[TMP1:%.*]] = fmul fast float [[DOTCAST]], 5.000000e-01
; VEC1_INTERL2-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP1]], [[INIT:%.*]]
@@ -670,11 +670,11 @@ define void @fp_iv_loop2(float %init, ptr noalias nocapture %A, i32 %N) #0 {
; VEC2_INTERL1_PRED_STORE-NEXT: [[CMP4:%.*]] = icmp sgt i32 [[N:%.*]], 0
; VEC2_INTERL1_PRED_STORE-NEXT: br i1 [[CMP4]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_END:%.*]]
; VEC2_INTERL1_PRED_STORE: for.body.preheader:
-; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP0:%.*]] = zext i32 [[N]] to i64
+; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP0:%.*]] = zext nneg i32 [[N]] to i64
; VEC2_INTERL1_PRED_STORE-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC2_INTERL1_PRED_STORE-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[FOR_BODY:%.*]], label [[VECTOR_PH:%.*]]
; VEC2_INTERL1_PRED_STORE: vector.ph:
-; VEC2_INTERL1_PRED_STORE-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 4294967294
+; VEC2_INTERL1_PRED_STORE-NEXT: [[N_VEC:%.*]] = and i64 [[TMP0]], 2147483646
; VEC2_INTERL1_PRED_STORE-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC2_INTERL1_PRED_STORE-NEXT: [[TMP1:%.*]] = fmul fast float [[DOTCAST]], 5.000000e-01
; VEC2_INTERL1_PRED_STORE-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP1]], [[INIT:%.*]]
@@ -753,11 +753,11 @@ define void @fp_iv_loop3(float %init, ptr noalias nocapture %A, ptr noalias noca
; VEC4_INTERL1-NEXT: br i1 [[CMP9]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL1: for.body.lr.ph:
; VEC4_INTERL1-NEXT: [[TMP0:%.*]] = load float, ptr @fp_inc, align 4
-; VEC4_INTERL1-NEXT: [[TMP1:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL1-NEXT: [[TMP1:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL1-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 4
; VEC4_INTERL1-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL1: vector.ph:
-; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP1]], 4294967292
+; VEC4_INTERL1-NEXT: [[N_VEC:%.*]] = and i64 [[TMP1]], 2147483644
; VEC4_INTERL1-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL1-NEXT: [[TMP2:%.*]] = fmul fast float [[DOTCAST]], -5.000000e-01
; VEC4_INTERL1-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP2]], 0x3FB99999A0000000
@@ -830,11 +830,11 @@ define void @fp_iv_loop3(float %init, ptr noalias nocapture %A, ptr noalias noca
; VEC4_INTERL2-NEXT: br i1 [[CMP9]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC4_INTERL2: for.body.lr.ph:
; VEC4_INTERL2-NEXT: [[TMP0:%.*]] = load float, ptr @fp_inc, align 4
-; VEC4_INTERL2-NEXT: [[TMP1:%.*]] = zext i32 [[N]] to i64
+; VEC4_INTERL2-NEXT: [[TMP1:%.*]] = zext nneg i32 [[N]] to i64
; VEC4_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[N]], 8
; VEC4_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC4_INTERL2: vector.ph:
-; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP1]], 4294967288
+; VEC4_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP1]], 2147483640
; VEC4_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC4_INTERL2-NEXT: [[TMP2:%.*]] = fmul fast float [[DOTCAST]], -5.000000e-01
; VEC4_INTERL2-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP2]], 0x3FB99999A0000000
@@ -917,11 +917,11 @@ define void @fp_iv_loop3(float %init, ptr noalias nocapture %A, ptr noalias noca
; VEC1_INTERL2-NEXT: br i1 [[CMP9]], label [[FOR_BODY_LR_PH:%.*]], label [[FOR_END:%.*]]
; VEC1_INTERL2: for.body.lr.ph:
; VEC1_INTERL2-NEXT: [[TMP0:%.*]] = load float, ptr @fp_inc, align 4
-; VEC1_INTERL2-NEXT: [[TMP1:%.*]] = zext i32 [[N]] to i64
+; VEC1_INTERL2-NEXT: [[TMP1:%.*]] = zext nneg i32 [[N]] to i64
; VEC1_INTERL2-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i32 [[N]], 1
; VEC1_INTERL2-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; VEC1_INTERL2: vector.ph:
-; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP1]], 4294967294
+; VEC1_INTERL2-NEXT: [[N_VEC:%.*]] = and i64 [[TMP1]], 2147483646
; VEC1_INTERL2-NEXT: [[DOTCAST:%.*]] = sitofp i64 [[N_VEC]] to float
; VEC1_INTERL2-NEXT: [[TMP2:%.*]] = fmul fast float [[DOTCAST]], -5.000000e-01
; VEC1_INTERL2-NEXT: [[IND_END:%.*]] = fadd fast float [[TMP2]], 0x3FB99999A0000000
@@ -995,11 +995,11 @@ define void @fp_iv_loop3(float %init, ptr noalias nocaptu...
[truncated]
|
You can test this locally with the following command:git-clang-format --diff d0ae2391897033c50225a20fd3024816dffd80b6 56067881febb110166f307fdce3aa446e6363e77 -- llvm/lib/Analysis/ValueTracking.cppView the diff from clang-format here.diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 22e88cb2f5..3443bd2b12 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -297,8 +297,8 @@ bool llvm::isKnownNonNegative(const Value *V, const DataLayout &DL,
// Look at the immediate proceeding branch to see if it establishes the
// condition we need.
return isImpliedByDomCondition(ICmpInst::ICMP_SGE, V,
- Constant::getNullValue(V->getType()), CxtI,
- DL).value_or(false);
+ Constant::getNullValue(V->getType()), CxtI, DL)
+ .value_or(false);
}
bool llvm::isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth,
|
|
Duplicate of #72049 |
I don't agree here. This is some overlap, but this patch is narrower in scope, and is motivated by the desire to simplify a particular bit of client code from #72431. I think this is a very worthwhile practical trade off. Non-negative zexts in loop pre-headers is pretty much the canonical use case for nneg. Having to do expensive analysis (as opposed to isKnownX) for these cases seems like overkill, and as seen in the linked patch, creates nasty pass ordering problems. |
|
Abandoning due to lack of progress in review and low priority. |
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This handles the idiomatic case of an instruction in the preheader of a loop with a loop guard on whether the starting value of the IV is non negative.
Note that we have many other examples of isKnownX queries which perform tree walks to try and prove the required condition. This patch is quite limited in checking only an immediate guarding condition.