Assertion `(PDiffI->getUnitInc() >= 0) == (PNew >= POld) && "PSet overflow/underflow"' failed.

[XChy]

The reduced testcase below triggers an assertion in the trunk:

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define i64 @e(i64 %vecext) {
entry:
  callbr void asm sideeffect "", "!i,~{dirflag},~{fpsr},~{flags}"()
          to label %g.preheader [label %g.preheader]

g.preheader:                                      ; preds = %entry, %entry
  store i64 0, ptr null, align 8
  tail call void asm sideeffect "", "~{rax},~{eax},~{dirflag},~{fpsr},~{flags}"()
  %rem = srem i64 705425148255374, %vecext
  ret i64 %rem
}

Compiler dump:

llc: /home/xchy/Projects/llvm-project/llvm/lib/CodeGen/RegisterPressure.cpp:1170: void llvm::RegPressureTracker::getUpwardPressureDelta(const llvm::MachineInstr*, llvm::PressureDiff&, llvm::RegPressureDelta&, llvm::ArrayR
ef<llvm::PressureChange>, llvm::ArrayRef<unsigned int>) const: Assertion `(PDiffI->getUnitInc() >= 0) == (PNew >= POld) && "PSet overflow/underflow"' failed.

https://godbolt.org/z/jf61qz184

[XChy]

A minimal testcase:

define i64 @e(i64 %vecext) {
entry:
  tail call void asm sideeffect "", "~{rax},~{eax},~{dirflag},~{fpsr},~{flags}"()
  %rem = srem i64 705425148255374, %vecext
  ret i64 %rem
}

[llvmbot]

@llvm/issue-subscribers-backend-x86

Author: XChy (XChy)

The reduced testcase below triggers an assertion in the trunk: ```llvm target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu"

define i64 @e(i64 %vecext) {
entry:
callbr void asm sideeffect "", "!i,{dirflag},{fpsr},~{flags}"()
to label %g.preheader [label %g.preheader]

g.preheader: ; preds = %entry, %entry
store i64 0, ptr null, align 8
tail call void asm sideeffect "", "{rax},{eax},{dirflag},{fpsr},~{flags}"()
%rem = srem i64 705425148255374, %vecext
ret i64 %rem
}

Compiler dump:

llc: /home/xchy/Projects/llvm-project/llvm/lib/CodeGen/RegisterPressure.cpp:1170: void llvm::RegPressureTracker::getUpwardPressureDelta(const llvm::MachineInstr*, llvm::PressureDiff&, llvm::RegPressureDelta&, llvm::ArrayR
ef<llvm::PressureChange>, llvm::ArrayRef<unsigned int>) const: Assertion `(PDiffI->getUnitInc() >= 0) == (PNew >= POld) && "PSet overflow/underflow"' failed.

https://godbolt.org/z/jf61qz184
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