[llvm] 42b3483 - ValueTracking: Improve accuracy of 0 handling with PreserveSign (#173165)
via llvm-commits
llvm-commits at lists.llvm.org
Sun Dec 21 03:14:29 PST 2025
Author: Matt Arsenault
Date: 2025-12-21T11:14:24Z
New Revision: 42b3483ac4987cae1bdb632398e8a3ce2dea6633
URL: https://github.com/llvm/llvm-project/commit/42b3483ac4987cae1bdb632398e8a3ce2dea6633
DIFF: https://github.com/llvm/llvm-project/commit/42b3483ac4987cae1bdb632398e8a3ce2dea6633.diff
LOG: ValueTracking: Improve accuracy of 0 handling with PreserveSign (#173165)
If the source value is known not subnormal and not zero with the
same sign, we can infer the result is also not zero with the same
sign.
Added:
Modified:
llvm/lib/Analysis/ValueTracking.cpp
llvm/test/Transforms/Attributor/nofpclass-canonicalize.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index d3d2a3db66ddc..0321c08f55776 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -5308,6 +5308,14 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
if (DenormMode.inputsAreZero() || DenormMode.outputsAreZero())
Known.knownNot(fcSubnormal);
+ if (DenormMode == DenormalMode::getPreserveSign()) {
+ if (KnownSrc.isKnownNever(fcPosZero | fcPosSubnormal))
+ Known.knownNot(fcPosZero);
+ if (KnownSrc.isKnownNever(fcNegZero | fcNegSubnormal))
+ Known.knownNot(fcNegZero);
+ break;
+ }
+
if (DenormMode.Input == DenormalMode::PositiveZero ||
(DenormMode.Output == DenormalMode::PositiveZero &&
DenormMode.Input == DenormalMode::IEEE))
diff --git a/llvm/test/Transforms/Attributor/nofpclass-canonicalize.ll b/llvm/test/Transforms/Attributor/nofpclass-canonicalize.ll
index 8a31bef83b68e..d1879cbb9add9 100644
--- a/llvm/test/Transforms/Attributor/nofpclass-canonicalize.ll
+++ b/llvm/test/Transforms/Attributor/nofpclass-canonicalize.ll
@@ -204,9 +204,9 @@ define float @ret_canonicalize_ieee_constant_snan() "denormal-fp-math"="ieee,iee
}
define float @ret_canonicalize_daz_constant_pos_denormal() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan inf sub norm) float @ret_canonicalize_daz_constant_pos_denormal
+; CHECK-LABEL: define noundef nofpclass(nan inf nzero sub norm) float @ret_canonicalize_daz_constant_pos_denormal
; CHECK-SAME: () #[[ATTR10:[0-9]+]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf sub norm) float @llvm.canonicalize.f32(float noundef 0x36A0000000000000) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf nzero sub norm) float @llvm.canonicalize.f32(float noundef 0x36A0000000000000) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0x36A0000000000000)
@@ -214,9 +214,9 @@ define float @ret_canonicalize_daz_constant_pos_denormal() "denormal-fp-math"="p
}
define float @ret_canonicalize_daz_constant_neg_denormal() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan inf sub norm) float @ret_canonicalize_daz_constant_neg_denormal
+; CHECK-LABEL: define noundef nofpclass(nan inf pzero sub norm) float @ret_canonicalize_daz_constant_neg_denormal
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf sub norm) float @llvm.canonicalize.f32(float noundef 0xB6A0000000000000) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf pzero sub norm) float @llvm.canonicalize.f32(float noundef 0xB6A0000000000000) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0xb6A0000000000000)
@@ -224,9 +224,9 @@ define float @ret_canonicalize_daz_constant_neg_denormal() "denormal-fp-math"="p
}
define float @ret_canonicalize_daz_constant_pos_zero() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan inf sub norm) float @ret_canonicalize_daz_constant_pos_zero
+; CHECK-LABEL: define noundef nofpclass(nan inf nzero sub norm) float @ret_canonicalize_daz_constant_pos_zero
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf sub norm) float @llvm.canonicalize.f32(float noundef 0.000000e+00) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf nzero sub norm) float @llvm.canonicalize.f32(float noundef 0.000000e+00) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0.0)
@@ -234,9 +234,9 @@ define float @ret_canonicalize_daz_constant_pos_zero() "denormal-fp-math"="prese
}
define float @ret_canonicalize_daz_constant_neg_zero() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan inf sub norm) float @ret_canonicalize_daz_constant_neg_zero
+; CHECK-LABEL: define noundef nofpclass(nan inf pzero sub norm) float @ret_canonicalize_daz_constant_neg_zero
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf sub norm) float @llvm.canonicalize.f32(float noundef -0.000000e+00) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf pzero sub norm) float @llvm.canonicalize.f32(float noundef -0.000000e+00) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float -0.0)
@@ -244,9 +244,9 @@ define float @ret_canonicalize_daz_constant_neg_zero() "denormal-fp-math"="prese
}
define float @ret_canonicalize_daz_constant_pos_normal() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan inf sub nnorm) float @ret_canonicalize_daz_constant_pos_normal
+; CHECK-LABEL: define noundef nofpclass(nan inf zero sub nnorm) float @ret_canonicalize_daz_constant_pos_normal
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf sub nnorm) float @llvm.canonicalize.f32(float noundef 8.000000e+00) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf zero sub nnorm) float @llvm.canonicalize.f32(float noundef 8.000000e+00) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 8.0)
@@ -254,9 +254,9 @@ define float @ret_canonicalize_daz_constant_pos_normal() "denormal-fp-math"="pre
}
define float @ret_canonicalize_daz_constant_neg_normal() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan inf sub pnorm) float @ret_canonicalize_daz_constant_neg_normal
+; CHECK-LABEL: define noundef nofpclass(nan inf zero sub pnorm) float @ret_canonicalize_daz_constant_neg_normal
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf sub pnorm) float @llvm.canonicalize.f32(float noundef -8.000000e+00) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan inf zero sub pnorm) float @llvm.canonicalize.f32(float noundef -8.000000e+00) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float -8.0)
@@ -264,9 +264,9 @@ define float @ret_canonicalize_daz_constant_neg_normal() "denormal-fp-math"="pre
}
define float @ret_canonicalize_daz_constant_pos_inf() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan ninf sub norm) float @ret_canonicalize_daz_constant_pos_inf
+; CHECK-LABEL: define noundef nofpclass(nan ninf zero sub norm) float @ret_canonicalize_daz_constant_pos_inf
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan ninf sub norm) float @llvm.canonicalize.f32(float noundef 0x7FF0000000000000) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan ninf zero sub norm) float @llvm.canonicalize.f32(float noundef 0x7FF0000000000000) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0x7FF0000000000000)
@@ -274,9 +274,9 @@ define float @ret_canonicalize_daz_constant_pos_inf() "denormal-fp-math"="preser
}
define float @ret_canonicalize_daz_constant_neg_inf() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(nan pinf sub norm) float @ret_canonicalize_daz_constant_neg_inf
+; CHECK-LABEL: define noundef nofpclass(nan pinf zero sub norm) float @ret_canonicalize_daz_constant_neg_inf
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan pinf sub norm) float @llvm.canonicalize.f32(float noundef 0xFFF0000000000000) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(nan pinf zero sub norm) float @llvm.canonicalize.f32(float noundef 0xFFF0000000000000) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0xFFF0000000000000)
@@ -284,9 +284,9 @@ define float @ret_canonicalize_daz_constant_neg_inf() "denormal-fp-math"="preser
}
define float @ret_canonicalize_daz_constant_qnan() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(snan inf sub norm) float @ret_canonicalize_daz_constant_qnan
+; CHECK-LABEL: define noundef nofpclass(snan inf zero sub norm) float @ret_canonicalize_daz_constant_qnan
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(snan inf sub norm) float @llvm.canonicalize.f32(float noundef 0x7FF8000000000000) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(snan inf zero sub norm) float @llvm.canonicalize.f32(float noundef 0x7FF8000000000000) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0x7FF8000000000000)
@@ -294,9 +294,9 @@ define float @ret_canonicalize_daz_constant_qnan() "denormal-fp-math"="preserve-
}
define float @ret_canonicalize_daz_constant_snan() "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define noundef nofpclass(snan inf sub norm) float @ret_canonicalize_daz_constant_snan
+; CHECK-LABEL: define noundef nofpclass(snan inf zero sub norm) float @ret_canonicalize_daz_constant_snan
; CHECK-SAME: () #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(snan inf sub norm) float @llvm.canonicalize.f32(float noundef 0x7FF1000000000000) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call noundef nofpclass(snan inf zero sub norm) float @llvm.canonicalize.f32(float noundef 0x7FF1000000000000) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float 0x7FF1000000000000)
@@ -504,9 +504,9 @@ define float @ret_canonicalize_dynamic_constant_snan() "denormal-fp-math"="dynam
}
define float @ret_canonicalize_daz_not_nzero_not_nsub(float nofpclass(nzero nsub) %x) "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define nofpclass(snan sub) float @ret_canonicalize_daz_not_nzero_not_nsub
+; CHECK-LABEL: define nofpclass(snan nzero sub) float @ret_canonicalize_daz_not_nzero_not_nsub
; CHECK-SAME: (float nofpclass(nzero nsub) [[X:%.*]]) #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(snan sub) float @llvm.canonicalize.f32(float nofpclass(nzero nsub) [[X]]) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(snan nzero sub) float @llvm.canonicalize.f32(float nofpclass(nzero nsub) [[X]]) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float %x)
@@ -534,9 +534,9 @@ define float @ret_canonicalize_daz_not_nzero(float nofpclass(nzero) %x) "denorma
}
define float @ret_canonicalize_daz_not_pzero_not_psub(float nofpclass(pzero psub) %x) "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define nofpclass(snan sub) float @ret_canonicalize_daz_not_pzero_not_psub
+; CHECK-LABEL: define nofpclass(snan pzero sub) float @ret_canonicalize_daz_not_pzero_not_psub
; CHECK-SAME: (float nofpclass(pzero psub) [[X:%.*]]) #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(snan sub) float @llvm.canonicalize.f32(float nofpclass(pzero psub) [[X]]) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(snan pzero sub) float @llvm.canonicalize.f32(float nofpclass(pzero psub) [[X]]) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float %x)
@@ -584,9 +584,9 @@ define float @ret_canonicalize_daz_not_sub(float nofpclass(sub) %x) "denormal-fp
}
define float @ret_canonicalize_daz_not_sub_not_nzero(float nofpclass(sub nzero) %x) "denormal-fp-math"="preserve-sign,preserve-sign" {
-; CHECK-LABEL: define nofpclass(snan sub) float @ret_canonicalize_daz_not_sub_not_nzero
+; CHECK-LABEL: define nofpclass(snan nzero sub) float @ret_canonicalize_daz_not_sub_not_nzero
; CHECK-SAME: (float nofpclass(nzero sub) [[X:%.*]]) #[[ATTR10]] {
-; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(snan sub) float @llvm.canonicalize.f32(float nofpclass(nzero sub) [[X]]) #[[ATTR12]]
+; CHECK-NEXT: [[CALL:%.*]] = call nofpclass(snan nzero sub) float @llvm.canonicalize.f32(float nofpclass(nzero sub) [[X]]) #[[ATTR12]]
; CHECK-NEXT: ret float [[CALL]]
;
%call = call float @llvm.canonicalize.f32(float %x)
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