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target/123137 - improve TLS call placement validity check

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When we search for a point in an inseration candidate block that has
incoming live call clobbered regs we look for REG_DEAD notes of
those and indication of FLAGS reg becoming live.  But we consider
insns like

(insn 807 805 6 2 (parallel [
            (set (subreg:SI (reg:HI 509) 0)
                (lshiftrt:SI (reg:SI 514)
                    (const_int 16 [0x10])))
            (clobber (reg:CC 17 flags))
        ]) "/home/packages/tmp/onednn-3.9.1+ds/src/cpu/x64/brgemm/jit_brgemm_amx_uker.cpp":1891:25 1213 {*lshrsi3_1}
     (expr_list:REG_UNUSED (reg:CC 17 flags)
        (expr_list:REG_DEAD (reg:SI 514)
            (nil))))

making the FLAGS_REG live despite the REG_UNUSED note or the setter
being a CLOBBER.  The following optimizes this by in turn honoring
REG_UNUSED for FLAGS_REG, pruning it immediately again.

This reduces required expensive iteration to other candidate BBs,
reducing compile-time for the testcase in the PR from hours to 6s.

	PR target/123137
	* config/i386/i386-features.cc (ix86_emit_tls_call): Improve
	local FLAGS_REG liveness calculation.

	* g++.dg/torture/pr124137.C: New testcase.
This commit is contained in:
Richard Biener
2026-02-18 10:05:02 +01:00
committed by Richard Biener
parent 2206271ead
commit d96b9b689f
2 changed files with 44 additions and 1 deletions
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4
gcc/config/i386/i386-features.cc
View File

@@ -4083,7 +4083,9 @@ ix86_emit_tls_call (rtx tls_set, x86_cse_kind kind, basic_block bb,
rtx link;
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
if (REG_NOTE_KIND (link) == REG_DEAD
if ((REG_NOTE_KIND (link) == REG_DEAD
|| (REG_NOTE_KIND (link) == REG_UNUSED
&& REGNO (XEXP (link, 0)) == FLAGS_REG))
&& REG_P (XEXP (link, 0)))
{
/* Mark the live caller-saved register as dead. */

41
gcc/testsuite/g++.dg/torture/pr124137.C Normal file
View File

@@ -0,0 +1,41 @@
// { dg-do compile }
// { dg-require-effective-target fpic }
// { dg-additional-options "-fPIC" }
inline int &GetErrorRef() {
thread_local int err;
return err;
}
int SetError_err;
bool isREG___trans_tmp_4;
struct Operand {
int : 6;
int kind_ : 10;
int bit_ : 14;
protected:
int : 11;
public:
bool isREG(int bit) {
isREG___trans_tmp_4 = kind_ && bit_ & bit;
return isREG___trans_tmp_4;
}
int getBit() { return bit_; }
};
struct Reg : Operand {
} index_, fp8_to_f16_upconvert_to_vnni_reg_data;
enum { i32e = 4 };
struct RegExp {
RegExp(Reg &r) {
if (r.isREG(i32e))
GetErrorRef() = SetError_err;
if (r.getBit())
index_ = r;
}
};
struct X {
void operator[](RegExp);
} ptr;
void jit_brgemm_amx_uker_base_tfp8_to_f16_upconvert_to_vnni(Reg reg_buf) {
RegExp __trans_tmp_3 = fp8_to_f16_upconvert_to_vnni_reg_data;
ptr[reg_buf];
}