[llvm] [X86] ICMP EQ/NE MIN_SIGNED_INT - avoid immediate argument by using NEG + SETO/SETNO (PR #94948)
Simon Pilgrim via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 10 02:51:43 PDT 2024
https://github.com/RKSimon created https://github.com/llvm/llvm-project/pull/94948
For i64 this avoids loading a 64-bit value into register, for smaller registers this just avoids an immediate operand.
I've let this fold run for i8+i16 as well as i32+i64, despite there being less of a codesize saving.
Fixes #67709
>From 7bc8e876b0ff9c636609af258a4ff420fbd0c8be Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev at redking.me.uk>
Date: Mon, 10 Jun 2024 10:42:42 +0100
Subject: [PATCH] [X86] ICMP EQ/NE MIN_SIGNED_INT - avoid immediate argument by
using NEG + SETO/SETNO
Fixes #67709
---
llvm/lib/Target/X86/X86ISelLowering.cpp | 12 ++++++++++++
llvm/test/CodeGen/X86/2008-06-16-SubregsBug.ll | 4 ++--
llvm/test/CodeGen/X86/combine-sdiv.ll | 4 ++--
llvm/test/CodeGen/X86/is_fpclass.ll | 18 ++++++++++--------
llvm/test/CodeGen/X86/lsr-overflow.ll | 6 +++---
llvm/test/CodeGen/X86/shrink-compare-pgso.ll | 4 ++--
llvm/test/CodeGen/X86/shrink-compare.ll | 4 ++--
7 files changed, 33 insertions(+), 19 deletions(-)
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 2aec14e93d082..cb51952285e71 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -23816,6 +23816,18 @@ SDValue X86TargetLowering::emitFlagsForSetcc(SDValue Op0, SDValue Op1,
}
}
+ // Look for X == INT_MIN or X != INT_MIN. We can use NEG and test for
+ // overflow.
+ if (isMinSignedConstant(Op1)) {
+ EVT VT = Op0.getValueType();
+ SDVTList CmpVTs = DAG.getVTList(VT, MVT::i32);
+ X86::CondCode CondCode = CC == ISD::SETEQ ? X86::COND_O : X86::COND_NO;
+ X86CC = DAG.getTargetConstant(CondCode, dl, MVT::i8);
+ SDValue Neg =
+ DAG.getNode(X86ISD::SUB, dl, CmpVTs, DAG.getConstant(0, dl, VT), Op0);
+ return SDValue(Neg.getNode(), 1);
+ }
+
// Try to use the carry flag from the add in place of an separate CMP for:
// (seteq (add X, -1), -1). Similar for setne.
if (isAllOnesConstant(Op1) && Op0.getOpcode() == ISD::ADD &&
diff --git a/llvm/test/CodeGen/X86/2008-06-16-SubregsBug.ll b/llvm/test/CodeGen/X86/2008-06-16-SubregsBug.ll
index feaa38a7600a2..00ffea903079e 100644
--- a/llvm/test/CodeGen/X86/2008-06-16-SubregsBug.ll
+++ b/llvm/test/CodeGen/X86/2008-06-16-SubregsBug.ll
@@ -8,8 +8,8 @@ define i16 @test(ptr %tmp179) nounwind {
; CHECK-NEXT: movzwl (%eax), %eax
; CHECK-NEXT: movl %eax, %ecx
; CHECK-NEXT: andl $64512, %ecx ## imm = 0xFC00
-; CHECK-NEXT: cmpl $32768, %ecx ## imm = 0x8000
-; CHECK-NEXT: jne LBB0_2
+; CHECK-NEXT: negw %cx
+; CHECK-NEXT: jno LBB0_2
; CHECK-NEXT: ## %bb.1: ## %bb189
; CHECK-NEXT: ## kill: def $ax killed $ax killed $eax
; CHECK-NEXT: retl
diff --git a/llvm/test/CodeGen/X86/combine-sdiv.ll b/llvm/test/CodeGen/X86/combine-sdiv.ll
index 49797fbefa597..5c5487815b336 100644
--- a/llvm/test/CodeGen/X86/combine-sdiv.ll
+++ b/llvm/test/CodeGen/X86/combine-sdiv.ll
@@ -58,8 +58,8 @@ define i32 @combine_sdiv_by_minsigned(i32 %x) {
; CHECK-LABEL: combine_sdiv_by_minsigned:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
-; CHECK-NEXT: cmpl $-2147483648, %edi # imm = 0x80000000
-; CHECK-NEXT: sete %al
+; CHECK-NEXT: negl %edi
+; CHECK-NEXT: seto %al
; CHECK-NEXT: retq
%1 = sdiv i32 %x, -2147483648
ret i32 %1
diff --git a/llvm/test/CodeGen/X86/is_fpclass.ll b/llvm/test/CodeGen/X86/is_fpclass.ll
index 2046d790cc57e..780341c4b6821 100644
--- a/llvm/test/CodeGen/X86/is_fpclass.ll
+++ b/llvm/test/CodeGen/X86/is_fpclass.ll
@@ -936,15 +936,16 @@ entry:
define i1 @is_minus_zero_f(float %x) {
; CHECK-32-LABEL: is_minus_zero_f:
; CHECK-32: # %bb.0: # %entry
-; CHECK-32-NEXT: cmpl $-2147483648, {{[0-9]+}}(%esp) # imm = 0x80000000
-; CHECK-32-NEXT: sete %al
+; CHECK-32-NEXT: xorl %eax, %eax
+; CHECK-32-NEXT: cmpl {{[0-9]+}}(%esp), %eax
+; CHECK-32-NEXT: seto %al
; CHECK-32-NEXT: retl
;
; CHECK-64-LABEL: is_minus_zero_f:
; CHECK-64: # %bb.0: # %entry
; CHECK-64-NEXT: movd %xmm0, %eax
-; CHECK-64-NEXT: cmpl $-2147483648, %eax # imm = 0x80000000
-; CHECK-64-NEXT: sete %al
+; CHECK-64-NEXT: negl %eax
+; CHECK-64-NEXT: seto %al
; CHECK-64-NEXT: retq
entry:
%0 = tail call i1 @llvm.is.fpclass.f32(float %x, i32 32) ; 0x20 = "-zero"
@@ -954,15 +955,16 @@ entry:
define i1 @not_is_minus_zero_f(float %x) {
; CHECK-32-LABEL: not_is_minus_zero_f:
; CHECK-32: # %bb.0: # %entry
-; CHECK-32-NEXT: cmpl $-2147483648, {{[0-9]+}}(%esp) # imm = 0x80000000
-; CHECK-32-NEXT: setne %al
+; CHECK-32-NEXT: xorl %eax, %eax
+; CHECK-32-NEXT: cmpl {{[0-9]+}}(%esp), %eax
+; CHECK-32-NEXT: setno %al
; CHECK-32-NEXT: retl
;
; CHECK-64-LABEL: not_is_minus_zero_f:
; CHECK-64: # %bb.0: # %entry
; CHECK-64-NEXT: movd %xmm0, %eax
-; CHECK-64-NEXT: cmpl $-2147483648, %eax # imm = 0x80000000
-; CHECK-64-NEXT: setne %al
+; CHECK-64-NEXT: negl %eax
+; CHECK-64-NEXT: setno %al
; CHECK-64-NEXT: retq
entry:
%0 = tail call i1 @llvm.is.fpclass.f32(float %x, i32 991) ; ~0x20 = ~"-zero"
diff --git a/llvm/test/CodeGen/X86/lsr-overflow.ll b/llvm/test/CodeGen/X86/lsr-overflow.ll
index 09c1c07ef3de0..79440c282be75 100644
--- a/llvm/test/CodeGen/X86/lsr-overflow.ll
+++ b/llvm/test/CodeGen/X86/lsr-overflow.ll
@@ -4,9 +4,9 @@
; The comparison uses the pre-inc value, which could lead LSR to
; try to compute -INT64_MIN.
-; CHECK: movabsq $-9223372036854775808, %rax
-; CHECK: cmpq %rax,
-; CHECK: sete %al
+; CHECK-NOT: movabsq $-9223372036854775808, %rax
+; CHECK: negq %r
+; CHECK-NEXT: seto %al
declare i64 @bar()
diff --git a/llvm/test/CodeGen/X86/shrink-compare-pgso.ll b/llvm/test/CodeGen/X86/shrink-compare-pgso.ll
index 254b8fe3fc6e3..5a15ee36c0726 100644
--- a/llvm/test/CodeGen/X86/shrink-compare-pgso.ll
+++ b/llvm/test/CodeGen/X86/shrink-compare-pgso.ll
@@ -265,8 +265,8 @@ if.end:
define dso_local void @test_sext_i8_icmp_neg128(i8 %x) nounwind !prof !14 {
; CHECK-LABEL: test_sext_i8_icmp_neg128:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: cmpb $-128, %dil
-; CHECK-NEXT: je bar # TAILCALL
+; CHECK-NEXT: negb %dil
+; CHECK-NEXT: jo bar # TAILCALL
; CHECK-NEXT: # %bb.1: # %if.end
; CHECK-NEXT: retq
entry:
diff --git a/llvm/test/CodeGen/X86/shrink-compare.ll b/llvm/test/CodeGen/X86/shrink-compare.ll
index 840167ff9f4a0..1a61451c26a03 100644
--- a/llvm/test/CodeGen/X86/shrink-compare.ll
+++ b/llvm/test/CodeGen/X86/shrink-compare.ll
@@ -265,8 +265,8 @@ if.end:
define dso_local void @test_sext_i8_icmp_neg128(i8 %x) nounwind minsize {
; CHECK-LABEL: test_sext_i8_icmp_neg128:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: cmpb $-128, %dil
-; CHECK-NEXT: je bar # TAILCALL
+; CHECK-NEXT: negb %dil
+; CHECK-NEXT: jo bar # TAILCALL
; CHECK-NEXT: # %bb.1: # %if.end
; CHECK-NEXT: retq
entry:
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