[llvm] [ValueTracking] Handle and/or of conditions in `computeKnownFPClassFromContext` (PR #118257)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw created https://github.com/llvm/llvm-project/pull/118257

Fix a typo introduced by  https://github.com/llvm/llvm-project/pull/83161.
This patch also supports decomposition of and/or expressions in `computeKnownFPClassFromContext`.


>From 688bb432c4b618de69a1d0e7807077a22f15762a Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Mon, 2 Dec 2024 13:50:56 +0800
Subject: [PATCH 1/2] [ValueTracking] Add pre-commit tests. NFC.

---
 .../InstCombine/fpclass-from-dom-cond.ll      | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll b/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll
index d6706d76056eea..f7e3748d0b4c2a 100644
--- a/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll
+++ b/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll
@@ -46,6 +46,32 @@ if.end:
   ret i1 %cmp.i
 }
 
+define i1 @test2_or(double %x, i1 %cond) {
+; CHECK-LABEL: define i1 @test2_or(
+; CHECK-SAME: double [[X:%.*]], i1 [[COND:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP:%.*]] = fcmp olt double [[X]], 0x3EB0C6F7A0000000
+; CHECK-NEXT:    [[OR:%.*]] = or i1 [[CMP]], [[COND]]
+; CHECK-NEXT:    br i1 [[OR]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    ret i1 false
+; CHECK:       if.end:
+; CHECK-NEXT:    [[CMP_I:%.*]] = fcmp oeq double [[X]], 0.000000e+00
+; CHECK-NEXT:    ret i1 [[CMP_I]]
+;
+entry:
+  %cmp = fcmp olt double %x, 0x3EB0C6F7A0000000
+  %or = or i1 %cmp, %cond
+  br i1 %or, label %if.then, label %if.end
+
+if.then:
+  ret i1 false
+
+if.end:
+  %cmp.i = fcmp oeq double %x, 0.000000e+00
+  ret i1 %cmp.i
+}
+
 define i1 @test3(float %x) {
 ; CHECK-LABEL: define i1 @test3(
 ; CHECK-SAME: float [[X:%.*]]) {

>From 07493fc354b686f0aca79d6f817091a757bd7cd5 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Mon, 2 Dec 2024 13:53:32 +0800
Subject: [PATCH 2/2] [ValueTracking] Handle and/or of conditions in
 `computeKnownFPClassFromCond`

---
 llvm/lib/Analysis/ValueTracking.cpp                    |  9 ++++++++-
 .../Transforms/InstCombine/fpclass-from-dom-cond.ll    | 10 +++-------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c48068afc04816..f74109f4989cbb 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4885,6 +4885,13 @@ static void computeKnownFPClassFromCond(const Value *V, Value *Cond,
                                         bool CondIsTrue,
                                         const Instruction *CxtI,
                                         KnownFPClass &KnownFromContext) {
+  Value *A, *B;
+  if (CondIsTrue ? match(Cond, m_LogicalAnd(m_Value(A), m_Value(B)))
+                 : match(Cond, m_LogicalOr(m_Value(A), m_Value(B)))) {
+    computeKnownFPClassFromCond(V, A, CondIsTrue, CxtI, KnownFromContext);
+    computeKnownFPClassFromCond(V, B, CondIsTrue, CxtI, KnownFromContext);
+    return;
+  }
   CmpInst::Predicate Pred;
   Value *LHS;
   uint64_t ClassVal = 0;
@@ -10090,7 +10097,7 @@ void llvm::findValuesAffectedByCondition(
 
       if (HasRHSC && match(A, m_Intrinsic<Intrinsic::ctpop>(m_Value(X))))
         AddAffected(X);
-    } else if (match(Cond, m_FCmp(Pred, m_Value(A), m_Value(B)))) {
+    } else if (match(V, m_FCmp(Pred, m_Value(A), m_Value(B)))) {
       AddCmpOperands(A, B);
 
       // fcmp fneg(x), y
diff --git a/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll b/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll
index f7e3748d0b4c2a..141b44cbbb7a1f 100644
--- a/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll
+++ b/llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll
@@ -56,8 +56,7 @@ define i1 @test2_or(double %x, i1 %cond) {
 ; CHECK:       if.then:
 ; CHECK-NEXT:    ret i1 false
 ; CHECK:       if.end:
-; CHECK-NEXT:    [[CMP_I:%.*]] = fcmp oeq double [[X]], 0.000000e+00
-; CHECK-NEXT:    ret i1 [[CMP_I]]
+; CHECK-NEXT:    ret i1 false
 ;
 entry:
   %cmp = fcmp olt double %x, 0x3EB0C6F7A0000000
@@ -266,7 +265,6 @@ if.else:
   ret i1 false
 }
 
-; TODO: handle and/or conditions
 define i1 @test11_and(float %x, i1 %cond2) {
 ; CHECK-LABEL: define i1 @test11_and(
 ; CHECK-SAME: float [[X:%.*]], i1 [[COND2:%.*]]) {
@@ -274,8 +272,7 @@ define i1 @test11_and(float %x, i1 %cond2) {
 ; CHECK-NEXT:    [[AND:%.*]] = and i1 [[COND]], [[COND2]]
 ; CHECK-NEXT:    br i1 [[AND]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    [[RET1:%.*]] = fcmp oeq float [[X]], 0x7FF0000000000000
-; CHECK-NEXT:    ret i1 [[RET1]]
+; CHECK-NEXT:    ret i1 false
 ; CHECK:       if.else:
 ; CHECK-NEXT:    ret i1 false
 ;
@@ -290,7 +287,6 @@ if.else:
   ret i1 false
 }
 
-; TODO: handle and/or conditions
 define i1 @test12_or(float %x, i1 %cond2) {
 ; CHECK-LABEL: define i1 @test12_or(
 ; CHECK-SAME: float [[X:%.*]], i1 [[COND2:%.*]]) {
@@ -301,7 +297,7 @@ define i1 @test12_or(float %x, i1 %cond2) {
 ; CHECK:       if.then:
 ; CHECK-NEXT:    ret i1 false
 ; CHECK:       if.else:
-; CHECK-NEXT:    [[RET:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 783)
+; CHECK-NEXT:    [[RET:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 780)
 ; CHECK-NEXT:    ret i1 [[RET]]
 ;
 entry: