[llvm-branch-commits] [llvm] ValueTracking: Handle amdgcn_exp2 in computeKnownFPClass (PR #172495)
Matt Arsenault via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Tue Dec 16 07:04:14 PST 2025
https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/172495
The base exp handling looks pretty incomplete.
>From 2da01fc71bb84a4cfb3d01c8b199158597aaed78 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Tue, 16 Dec 2025 15:23:36 +0100
Subject: [PATCH] ValueTracking: Handle amdgcn_exp2 in computeKnownFPClass
The base exp handling looks pretty incomplete.
---
llvm/lib/Analysis/ValueTracking.cpp | 7 ++-
.../Attributor/AMDGPU/nofpclass-amdgcn-exp.ll | 48 +++++++++----------
2 files changed, 30 insertions(+), 25 deletions(-)
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 045cbab221ac3..0b57e27c92331 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -5374,7 +5374,8 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
}
case Intrinsic::exp:
case Intrinsic::exp2:
- case Intrinsic::exp10: {
+ case Intrinsic::exp10:
+ case Intrinsic::amdgcn_exp2: {
Known.knownNot(fcNegative);
if ((InterestedClasses & fcNan) == fcNone)
break;
@@ -5387,6 +5388,10 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
Known.signBitMustBeZero();
}
+ Type *EltTy = II->getType()->getScalarType();
+ if (IID == Intrinsic::amdgcn_exp2 && EltTy->isFloatTy())
+ Known.knownNot(fcSubnormal);
+
break;
}
case Intrinsic::fptrunc_round: {
diff --git a/llvm/test/Transforms/Attributor/AMDGPU/nofpclass-amdgcn-exp.ll b/llvm/test/Transforms/Attributor/AMDGPU/nofpclass-amdgcn-exp.ll
index babd1c68f161d..e7c41e9be7e33 100644
--- a/llvm/test/Transforms/Attributor/AMDGPU/nofpclass-amdgcn-exp.ll
+++ b/llvm/test/Transforms/Attributor/AMDGPU/nofpclass-amdgcn-exp.ll
@@ -4,9 +4,9 @@
declare float @llvm.amdgcn.exp2.f32(float)
define half @ret_exp_f16(half %arg0) {
-; CHECK-LABEL: define half @ret_exp_f16(
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) half @ret_exp_f16(
; CHECK-SAME: half [[ARG0:%.*]]) #[[ATTR1:[0-9]+]] {
-; CHECK-NEXT: [[CALL:%.*]] = call half @llvm.amdgcn.exp2.f16(half [[ARG0]]) #[[ATTR2:[0-9]+]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero nsub nnorm) half @llvm.amdgcn.exp2.f16(half [[ARG0]]) #[[ATTR2:[0-9]+]]
; CHECK-NEXT: ret half [[CALL]]
;
%call = call half @llvm.amdgcn.exp2.f16(half %arg0)
@@ -14,9 +14,9 @@ define half @ret_exp_f16(half %arg0) {
}
define float @ret_exp_f32(float %arg0) {
-; CHECK-LABEL: define float @ret_exp_f32(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @ret_exp_f32(
; CHECK-SAME: float [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -24,9 +24,9 @@ define float @ret_exp_f32(float %arg0) {
}
define float @ret_exp_noinf(float nofpclass(inf) %arg0) {
-; CHECK-LABEL: define float @ret_exp_noinf(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @ret_exp_noinf(
; CHECK-SAME: float nofpclass(inf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(inf) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(inf) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -34,9 +34,9 @@ define float @ret_exp_noinf(float nofpclass(inf) %arg0) {
}
define float @ret_exp_nopinf(float nofpclass(pinf) %arg0) {
-; CHECK-LABEL: define float @ret_exp_nopinf(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @ret_exp_nopinf(
; CHECK-SAME: float nofpclass(pinf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(pinf) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(pinf) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -44,9 +44,9 @@ define float @ret_exp_nopinf(float nofpclass(pinf) %arg0) {
}
define float @ret_exp_noninf(float nofpclass(ninf) %arg0) {
-; CHECK-LABEL: define float @ret_exp_noninf(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @ret_exp_noninf(
; CHECK-SAME: float nofpclass(ninf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(ninf) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(ninf) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -54,9 +54,9 @@ define float @ret_exp_noninf(float nofpclass(ninf) %arg0) {
}
define float @ret_exp_nonan(float nofpclass(nan) %arg0) {
-; CHECK-LABEL: define float @ret_exp_nonan(
+; CHECK-LABEL: define nofpclass(nan ninf nzero sub nnorm) float @ret_exp_nonan(
; CHECK-SAME: float nofpclass(nan) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(nan) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(nan ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(nan) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -64,9 +64,9 @@ define float @ret_exp_nonan(float nofpclass(nan) %arg0) {
}
define float @ret_exp_nonan_noinf(float nofpclass(nan inf) %arg0) {
-; CHECK-LABEL: define float @ret_exp_nonan_noinf(
+; CHECK-LABEL: define nofpclass(nan ninf nzero sub nnorm) float @ret_exp_nonan_noinf(
; CHECK-SAME: float nofpclass(nan inf) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(nan inf) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(nan ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(nan inf) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -74,9 +74,9 @@ define float @ret_exp_nonan_noinf(float nofpclass(nan inf) %arg0) {
}
define float @ret_exp_nonan_noinf_nozero(float nofpclass(nan inf zero) %arg0) {
-; CHECK-LABEL: define float @ret_exp_nonan_noinf_nozero(
+; CHECK-LABEL: define nofpclass(nan ninf nzero sub nnorm) float @ret_exp_nonan_noinf_nozero(
; CHECK-SAME: float nofpclass(nan inf zero) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(nan inf zero) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(nan ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(nan inf zero) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -84,9 +84,9 @@ define float @ret_exp_nonan_noinf_nozero(float nofpclass(nan inf zero) %arg0) {
}
define float @ret_exp_noinf_nozero(float nofpclass(inf zero) %arg0) {
-; CHECK-LABEL: define float @ret_exp_noinf_nozero(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @ret_exp_noinf_nozero(
; CHECK-SAME: float nofpclass(inf zero) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(inf zero) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(inf zero) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -94,9 +94,9 @@ define float @ret_exp_noinf_nozero(float nofpclass(inf zero) %arg0) {
}
define float @ret_exp_noinf_nonegzero(float nofpclass(inf nzero) %arg0) {
-; CHECK-LABEL: define float @ret_exp_noinf_nonegzero(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @ret_exp_noinf_nonegzero(
; CHECK-SAME: float nofpclass(inf nzero) [[ARG0:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float nofpclass(inf nzero) [[ARG0]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float nofpclass(inf nzero) [[ARG0]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.amdgcn.exp2.f32(float %arg0)
@@ -104,10 +104,10 @@ define float @ret_exp_noinf_nonegzero(float nofpclass(inf nzero) %arg0) {
}
define float @ret_exp_positive_source(i32 %arg) {
-; CHECK-LABEL: define float @ret_exp_positive_source(
+; CHECK-LABEL: define nofpclass(nan ninf nzero sub nnorm) float @ret_exp_positive_source(
; CHECK-SAME: i32 [[ARG:%.*]]) #[[ATTR1]] {
; CHECK-NEXT: [[UITOFP:%.*]] = uitofp i32 [[ARG]] to float
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float [[UITOFP]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(nan ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float [[UITOFP]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%uitofp = uitofp i32 %arg to float
@@ -117,10 +117,10 @@ define float @ret_exp_positive_source(i32 %arg) {
; Could produce a nan because we don't know if the multiply is negative.
define float @ret_exp_unknown_sign(float nofpclass(nan) %arg0, float nofpclass(nan) %arg1) {
-; CHECK-LABEL: define float @ret_exp_unknown_sign(
+; CHECK-LABEL: define nofpclass(nan ninf nzero sub nnorm) float @ret_exp_unknown_sign(
; CHECK-SAME: float nofpclass(nan) [[ARG0:%.*]], float nofpclass(nan) [[ARG1:%.*]]) #[[ATTR1]] {
; CHECK-NEXT: [[UNKNOWN_SIGN_NOT_NAN:%.*]] = fmul nnan float [[ARG0]], [[ARG1]]
-; CHECK-NEXT: [[CALL:%.*]] = call float @llvm.amdgcn.exp2.f32(float [[UNKNOWN_SIGN_NOT_NAN]]) #[[ATTR2]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(nan ninf nzero sub nnorm) float @llvm.amdgcn.exp2.f32(float [[UNKNOWN_SIGN_NOT_NAN]]) #[[ATTR2]]
; CHECK-NEXT: ret float [[CALL]]
;
%unknown.sign.not.nan = fmul nnan float %arg0, %arg1
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